Reducing Major Complications in Percutaneous Nephrolithotomy Through Surgical Standardization: A Retrospective Evaluation of 100 Cases and Review of the Literature

Reducing Major Complications in Percutaneous Nephrolithotomy Through Surgical Standardization: A Retrospective Evaluation of 100 Cases and Review of the Literature | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Reducing Major Complications in Percutaneous Nephrolithotomy Through Surgical Standardization: A Retrospective Evaluation of 100 Cases and Review of the Literature Hüseyin Biçer, Ömer Şahin, Burak Elmaağaç, Abdullah Golbasi, Mert Ali Karadag This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6973091/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objective: This study aims to assess the effectiveness of standardized preoperative, intraoperative, and postoperative protocols in preventing major complications (Clavien-Dindo grades 3–5) during percutaneous nephrolithotomy (PNL) procedures performed with micro, mini, and standard techniques in our clinic. Materials and Methods: A total of 100 consecutive patients who underwent PNL for renal calculi between April 2022 and January 2024 were retrospectively evaluated. Surgical approaches included micro, mini, and standard PNL, all performed by a single experienced surgeon. Patient demographics, stone characteristics, procedural details, complications, and outcomes were systematically analyzed. Results: No major complications were observed across all procedures. Standardized measures—such as careful selection of minimally invasive techniques, use of vacuum-assisted renal sheaths, preoperative sterile urine cultures, controlled intrarenal pressure, and intraoperative flexible endoscopic evaluation—were instrumental in reducing risk. Minor complications occurred in 11% of cases (grade 1) and 6% (grade 2). Logistic regression analysis identified lower stone density and higher Guy’s stone scores as independent predictors of postoperative complications. Conclusion: Implementing a comprehensive and standardized surgical protocol significantly minimized the incidence of major complications in PNL procedures. These findings suggest that clinical pathways emphasizing meticulous planning, imaging-based entry strategies, pressure control, and intraoperative assessments can substantially improve safety profiles. Multicenter prospective studies are warranted to further validate these outcomes. Percutaneous nephrolithotomy surgical standardization complication prevention Clavien-Dindo classification vacuum-assisted sheath intrarenal pressure control minimally invasive urologic surgery 1. Introduction Percutaneous nephrolithotomy (PNL) is the first-line treatment for renal calculi exceeding 2 cm in diameter, staghorn stones, multiple stones, or cases where extracorporeal shock wave lithotripsy (ESWL) and flexible ureteroscopy (FURS) have failed [ 1 ]. Since its introduction by Fernström and Johansson in 1976, PNL has become an essential modality in the surgical management of complex nephrolithiasis [ 2 ]. The first clinical series was published in 1979, and since the 1990s, both the European Association of Urology (EAU) and the American Urological Association (AUA) have endorsed PNL as the preferred treatment for large renal stones [ 3 ]. Depending on the diameter of the access sheath used, PNL procedures are typically classified as standard PNL (24–30 Fr), mini PNL (12–22 Fr for standard mini, 10–14 Fr for super mini, and 11–13 Fr for ultra-mini), and micro PNL (approximately 4.8 Fr) [ 4 ]. Advances in technology over the past decade have significantly enhanced procedural efficacy and safety. Innovations such as vacuum-assisted renal access sheaths and endoscopic vision-guided entry have contributed to improved outcomes and reduced complication rates. Despite these developments, serious complications—including hemorrhage, injury to adjacent organs, and infectious events—remain potential risks during PNL. In a study by Kyriazis et al. (2015), reported complication rates ranged widely, from 4–50%, reflecting the heterogeneity of practice and patient populations [ 5 ]. To standardize complication reporting, Tefekli and colleagues proposed an adapted version of the Clavien-Dindo classification specific to PNL in 2007, dividing outcomes into minor (grades 1–2) and major (grades 3–5) complications [ 6 ]. In our institution, a structured surgical protocol has been implemented to reduce variability and enhance procedural safety. By sharing the outcomes of the first 100 consecutive cases performed with micro, mini, and standard PNL techniques, we aim to contribute to the growing body of evidence supporting standardized strategies to mitigate perioperative risk in PNL. 2. Materials and Methods This retrospective observational study was conducted in accordance with the ethical principles of the Declaration of Helsinki and was approved by the Institutional Review Board of Kayseri City Training and Research Hospital (Approval No: 2024/116, dated May 14, 2024). Data were collected from patients who underwent percutaneous nephrolithotomy (PNL) between April 2022 and January 2024 due to renal calculi. All procedures were performed by a single high-volume endourologist(1000 PNL procedure with 15 years exprecience). Patients were categorized into three groups based on the type of PNL technique applied: Micro PNL Mini PNL Standard PNL Comprehensive evaluations were conducted for each group, comparing demographic characteristics, preoperative findings, intraoperative parameters, and postoperative outcomes. 2.1 Preoperative Assessment The choice of surgical technique was based on stone location, size, volume, Hounsfield unit (HU) density, surgeon’s experience, and institutional resources. All patients underwent preoperative non-contrast computed tomography (CT) to evaluate stone burden, HU density, number of stones, skin-to-stone distance, renal anatomical anomalies, and presence of retrorenal organs. Complex cases were further assessed with advanced imaging such as CT angiography or intravenous pyelography [7]. In cases of impaired renal function or cortical thinning, renal scintigraphy (DTPA or MAG-3) was performed [8]. Patients with severe cortical atrophy were managed with alternative treatment strategies. Nomograms such as the Guy’s, STONE, and CROES scoring systems were calculated preoperatively for each patient to estimate stone complexity and predict stone-free status. In addition, retrorenal organ positioning was evaluated via prone ultrasonography. Systemic comorbidities (e.g., diabetes mellitus, coronary artery disease, COPD), medication use, age, sex, body mass index (BMI), and spinal deformities were thoroughly reviewed for preoperative risk stratification. Surgical positioning was selected accordingly. Baseline laboratory parameters—complete blood count, serum creatinine, BUN, C-reactive protein (CRP), coagulation profile, and urinalysis—were obtained for all patients. Those receiving antiplatelet or anticoagulant therapy underwent preoperative cardiology consultation. Patients were operated on only after obtaining sterile urine cultures. Prophylactic intravenous administration of a third-generation cephalosporin was performed 30 minutes before the procedure. 2.2 Intraoperative Technique Anesthetic strategy was individualized based on patient status, position, and expected surgical duration. Modified prone split-leg positioning was routinely preferred for its advantages in renal access and simultaneous retrograde intervention. Silicon pads were used to optimize pulmonary ventilation, and careful arm positioning was ensured to avoid brachial plexus injury. Percutaneous access was guided by fluoroscopy, with an entry angle of 30° targeting the fornix and Brodel’s line to minimize bleeding risk. In suitable cases, endoscopic vision-guided access was performed to reduce fluoroscopy time and enhance safety. Upper pole punctures were conducted under tidal volume control in coordination with the anesthesia team to avoid pleural injury. Lower calyx access was generally preferred. A flexible nephroscope or ureterorenoscope was used to reduce trauma and improve visualization. During tract dilation, guidewire position was intermittently checked to prevent kinking or misplacement. Pneumatic or laser lithotripsy was performed under direct visualization, ensuring no injury to the collecting system. 2.3 Standardized Surgical Protocol for All PNL Modalities Lithotomy positioning under general anesthesia. Placement of access sheath or ureteral catheter (5–6 Fr) or vacuum-assisted ureteral sheath (9.5–11 Fr). In micro-PNL, if vacuum sheath insertion failed, a 6 Fr JJ stent was placed and the operation was postponed for two weeks. Transition to prone split-leg position with repeated sterile draping. Irrigation was maintained by gravity at ~1.5 meters above the patient using room temperature saline to control renal pelvic pressure. Fluoroscopy-guided puncture and tract dilation were carried out for standard and mini-PNL using appropriate access needles and Amplatz dilators. Instrumentation and energy modalities varied by PNL technique (detailed below). 2.4 Surgical Equipment and Techniques Standard PNL Dilation System: 30 Fr Amplatz renal dilator (Cook Medical™) Access Sheath: 30 Fr Amplatz renal sheath (Cook Medical™) Nephroscope: 24 Fr rigid nephroscope (Karl Storz™) Energy Source: EMS Swiss LithoClast® Master pneumatic lithotripter or 35 Watt Ho:YAG laser (Quanta System™, 550 µm fiber) Additional Instruments: 16 Fr, 30 cm Malecot re-entry catheter or 6 Fr, 26 cm double-J ureteral stent (Plasti-med™) Mini PNL Dilation System: 16 Fr Amplatz renal dilator (single-shot technique, Cook Medical™) Access Sheath: 16 Fr ClearPetra® vacuum-assisted sheath (Well Lead Medical™) Nephroscope: 12 Fr mini-nephroscope (Karl Storz™) Energy Source: 35 Watt Ho:YAG laser (Quanta System™, 550 µm fiber) Additional Instruments: 6 Fr ureteral catheter or 6 Fr, 26 cm double-J stent Micro PNL Access Sheath: Vacuum-assisted ureteral access sheath (connected to 200 mmHg suction) Nephroscope: 4.8 Fr “All-Seeing Needle” (Plasti-med™, 20 cm) Energy Source: 35 Watt Ho:YAG laser (Quanta System™, 272 µm fiber) Additional Instruments: 6 Fr ureteral catheter or 6 Fr, 26 cm double-J stent 2.5 Postoperative Management To minimize postoperative complications, all patients underwent close hemodynamic monitoring during the early recovery phase. Intravenous fluid support was administered, and empiric antibiotic therapy was initiated in patients presenting with fever. Pharmacologic prophylaxis against venous thromboembolism was applied in selected cases. Vital signs—including body temperature, heart rate, blood pressure, and respiratory rate—were recorded at regular intervals. Urine output and color were carefully observed for any signs of bleeding. In patients presenting with macroscopic hematuria or hypotension, angiographic evaluation and potential embolization were considered. Postoperative laboratory assessments included: Hemoglobin Blood urea nitrogen (BUN) Serum creatinine C-reactive protein (CRP) Coagulation parameters White blood cell count Radiological follow-up to assess residual stone fragments was conducted at postoperative day 30 using either non-contrast CT or plain kidney-ureter-bladder (KUB) radiography. Simultaneously, serum creatinine levels were reassessed to detect potential renal functional decline. Catheters and drains were removed based on clinical stability: The Foley catheter was withdrawn on postoperative day 1. Re-entry Malecot catheters were removed within 1–2 days if no fever or significant hematuria was noted. Ureteral stents were extracted within 2–3 weeks postoperatively. 2.6 Statistical Analysis All statistical analyses were performed using SPSS version 25.0 (IBM Corp., Armonk, NY, USA). Continuous variables were expressed as mean ± standard deviation and median values, while categorical variables were summarized as frequencies and percentages. To evaluate predictive factors for minor complications following PNL, logistic regression analysis was applied. Initially, univariate logistic regression was conducted to identify potential associations between preoperative and perioperative variables and postoperative complications. Variables with a p-value <0.05 in univariate analysis were further included in a multivariate logistic regression model to determine independent risk factors. A p-value of less than 0.05 was considered statistically significant in all analyses. 3. Results A total of 100 patients underwent PNL procedures using standard (n=40), mini (n=40), or micro (n=20) techniques. Detailed demographic, perioperative, and postoperative data for each group are summarized in Table 1 . No major complications (Clavien-Dindo grades 3–5) were observed in any of the procedures. Overall, 17 patients (17%) experienced minor complications. According to the Clavien-Dindo classification: Standard PNL group: Grade 1: 5 patients (fever n=3; transient rise in serum creatinine n=2) Grade 2: 4 patients (blood transfusion n=2; early postoperative urinary leakage n=2) Mini PNL group: Grade 1: 3 patients (fever n=2; transient creatinine elevation n=1) Grade 2: 1 patient (blood transfusion) Micro PNL group: Grade 1: 3 patients (fever n=2; transient creatinine elevation n=1) Grade 2: 1 patient (antibiotic-requiring urinary tract infection) Notably, no patient experienced grade 3 or higher complications across all PNL modalities. Patients who developed complications had significantly larger stone size and volume, but lower stone density (HU) compared to those without complications. Furthermore, elevated preoperative BUN and creatinine levels, along with lower hemoglobin and estimated glomerular filtration rate (eGFR), were more frequently observed in the complication group. Table 2 compares key demographic, clinical, and radiological parameters between patients with and without complications. To further investigate risk factors, logistic regression analysis was conducted. Univariate analysis identified four variables significantly associated with increased risk of complications: Larger stone size (p=0.022) Lower stone density (p=0.022) Decreased preoperative eGFR (p=0.017) Higher Guy’s stone score (p<0.001) In multivariate analysis , two independent predictors of minor postoperative complications were identified: Decreased stone density (OR: 0.997; 95% CI: 0.994–0.999; p=0.006) Elevated Guy’s stone score (OR: 53.360; 95% CI: 5.593–590.08; p=0.001) These findings are presented in Table 3 . 4. Discussion Percutaneous nephrolithotomy (PNL) has been the cornerstone surgical approach for managing renal calculi larger than 2 cm, multiple stones, staghorn calculi, or those refractory to ESWL or flexible ureteroscopy (FURS). 1 Despite being widely accepted and refined over decades, PNL remains technically demanding, associated with a steep learning curve and a risk of significant complications—particularly when performed by less experienced surgeons [ 9 ]. Both the European Association of Urology (EAU) and the American Urological Association (AUA) continue to endorse PNL as a first-line treatment for large renal stones. In addition, PNL is increasingly used in select cases such as symptomatic calyceal diverticular stones, failed FURS, and patients with urinary diversions or anatomical anomalies [ 10 ]. This study provides compelling evidence that surgical standardization can significantly reduce the rate of major complications during PNL. In our series of 100 consecutive cases, no Clavien-Dindo grade 3–5 complications were observed. These results contrast with existing literature, where complication rates after PNL vary between 8.1% and 19.6% depending on patient and procedural factors [ 11 ]. In a meta-analysis involving nearly 12,000 cases, reported complication rates were: fever (10.8%), transfusion (7%), thoracic complications (1.5%), sepsis (0.5%), visceral injury (0.4%), embolization (0.4%), urinoma (0.2%), and mortality (0.05%) [ 12 ]. The use of a modified Clavien-Dindo classification specific to PNL has enabled a more granular understanding of perioperative risks [ 13 ]. According to Seitz et al., Grade 1–2 events (%95.1) account for the majority of complications, while Grade ≥ 3 events (%4.9) are rare but clinically significant [ 12 ]. Hemorrhagic Complications Bleeding remains one of the most serious complications of PNL, ranging from mild hematuria to life-threatening hemorrhage requiring embolization [ 14 , 15 ]. Risk factors include solitary kidney, multiple tracts, large stone burden, prolonged operative time, active infection, and diabetes mellitus [ 16 ]. In our series, the mean hemoglobin drop was 0.99 ± 1.04 g/dL, and the transfusion rate was only 4%, notably lower than the 7% reported in literatüre [ 12 ]. We attribute this favorable outcome to our standardized surgical strategy: Pre-access planning based on CT measurements to avoid vascular injury Needle insertion targeting Brodel’s line Controlled dilation under direct endoscopic and fluoroscopic guidance Avoidance of excessive torque during nephroscopy Infectious Complications Fever occurred in 10% of cases, while urinary tract infections requiring antibiotics occurred in 2%. No cases of sepsis or septic shock were observed. This is significantly lower than previously reported rates ranging from 4.3–12.8% [ 17 ]. Key measures likely contributing to this outcome include: Ensuring negative preoperative urine culture Use of vacuum-assisted sheaths to reduce intrarenal pressure Collection of renal pelvic and stone cultures during surgery Postponement of procedures with pyuric aspirates until proper antibiotic therapy was initiated Tailored postoperative antibiotic regimens based on intraoperative culture results Vacuum-assisted access systems have been shown to maintain renal pelvic pressures below 6 cm H₂O, as opposed to pressures exceeding 100 cm H₂O with conventional mini-PNL sheaths [ 18 , 19 ]. Several studies including those by Zanetti et al. have reported reduced operative time and lower infection rates with these systems [ 20 , 21 ]. Visceral Injury No visceral organ injuries were encountered in our series. This may be attributed to preoperative evaluation of adjacent anatomy using CT and prone ultrasound, and the use of flexible nephroscopes to access upper pole stones rather than supracostal puncture. According to the literature, pleural injuries occur in ~ 1.5% and colonic injuries in ~ 0.4% of cases [ 12 ]. Importantly, none of the major complications defined by Tefekli et al. such as urinoma requiring stenting, pneumothorax, embolization, perinephric abscess, or nephrectomy—were observed in our cohort [ 6 ]. Protocol-Based Surgery: A Reproducible Model Perhaps the most important implication of our findings is the feasibility and effectiveness of a reproducible, checklist-driven surgical model for PNL. While most complications are multifactorial, we show that when the operative sequence is optimized and protocolized, adverse outcomes can be minimized regardless of the PNL subtype. This approach mirrors developments in other surgical disciplines, such as enhanced recovery after surgery (ERAS) protocols, and is consistent with the trend toward standardization in urologic oncology and reconstruction. For endourology to continue evolving, surgical reproducibility and safety should be as emphasized as efficacy. 5. Limitations This study has several limitations that must be acknowledged: Retrospective design : The non-randomized and retrospective nature of the study precludes strong causal inference and may introduce selection bias. Single-center, single-surgeon data : While ensuring procedural consistency, this limits generalizability to broader clinical environments with varying surgical expertise and institutional protocols. Sample size : Although 100 patients were included, the cohort may be underpowered to detect rare complications or to fully compare subgroups stratified by surgical technique. Short-term follow-up : The study lacked long-term postoperative surveillance, which prevents assessment of delayed complications, such as ureteral strictures, recurrent stone formation, or chronic renal impairment. 6. Conclusion Our findings demonstrate that implementing standardized surgical protocols—encompassing preoperative imaging-based planning, sterile urine control, optimized patient positioning, intraoperative pressure regulation using vacuum-assisted systems, and vigilant postoperative monitoring—can significantly reduce the risk of major complications in PNL procedures. The absence of Clavien-Dindo grade 3–5 events in our 100-patient cohort underscores the potential of protocol-driven interventions to enhance procedural safety. These results provide practical insight for urologic surgeons aiming to minimize perioperative risk and support the development of reproducible, low-complication clinical pathways in endourology. Future multicenter and prospective studies are warranted to validate these findings across different practice settings and to further refine PNL safety standards. Declarations Conflict of Interest The authors declare no conflicts of interest relevant to this study. Funding Statement This research received no external funding. Ethical Approval This study was conducted in accordance with the principles of the Declaration of Helsinki and was approved by the Institutional Review Board of Kayseri City Training and Research Hospital (Approval No: 2024/116; Date: May 14, 2024). Author Contributions Hüseyin Biçer: Conceptualization, Methodology, Surgery, Writing – original draft Ömer Şahin: Data curation, Formal analysis Burak Elmaağaç: Visualization, Literature review Abdullah Gölbaşı: Investigation, Data interpretation Mert Ali Karadağ: Statistical analysis, Editing References Ramakumar S, Segura JW (2000) Renal calculi. Percutaneous management. Urol Clin North Am 27(4):617–622 Fernstrom I, Johansson B (1976) Percutaneous pyelolithotomy: A new extraction technique. Scand J Urol Nephrol 10(3):257–259 Zeng G, Cai C, Duan X et al (2021) Mini percutaneous nephrolithotomy is a noninferior modality to standard percutaneous nephrolithotomy for the management of 20–40 mm renal calculi: A multicenter randomized controlled trial. Eur Urol 79(1):114–121. 10.1016/j.eururo.2020.09.026 Tzelves L, Skolarikos A (2020) Suction use during endourological procedures. Curr Urol Rep 21(11):46. 10.1007/s11934-020-00998-9 Kyriazis I, Panagopoulos V, Kallidonis P et al (2015) Complications in percutaneous nephrolithotomy. World J Urol 33(8):1069–1077. 10.1007/s00345-014-1400-8 Tefekli A, Karadag MA, Tepeler K et al (2008) Classification of percutaneous nephrolithotomy complications using the modified Clavien grading system: Looking for a standard. 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Exp Ther Med 21(3):213 Seitz C, Desai M, Häcker A et al (2012) Incidence, prevention, and management of complications following percutaneous nephrolitholapaxy. Eur Urol 61(1):146–158 Feng D, Hu X, Tang Y et al (2020) Miniaturized versus standard percutaneous nephrolithotomy: A systematic review and meta-analysis of RCTs. Investig Clin Urol 61(2):115–126 Sacha K, Szewczyk W, Bar K (1996) Massive hemorrhage as a complication after percutaneous nephrolithotomy. Int Urol Nephrol 28(3):315–318 Richstone L, Reggio E, Ost MC et al (2008) Hemorrhage following percutaneous renal surgery: Characterization of angiographic findings. J Endourol 22(6):1129–1135 Akman T, Binbay M, Sari E et al (2011) Factors affecting bleeding during percutaneous nephrolithotomy: A single surgeon’s experience. J Endourol 25(2):327–333 Rivera M, Viers B, Cockerill P et al (2016) Pre- and postoperative predictors of infection-related complications in patients undergoing percutaneous nephrolithotomy. J Endourol 30(9):982–986 Nagele U, Horstmann M, Sievert KD et al (2007) A newly designed amplatz sheath decreases intrapelvic pressure during mini-perc: In-vitro study. J Endourol 21(10):1113–1116 Yang Z, Song L, Xie D et al (2016) Mini-PCNL with suctioning device: Efficient and safe management of staghorn calculi. Urol Int 97(1):61–66 Chen D, Chen C, Xie Y et al (2021) Suctioning vs. traditional sheath in mini-PNL: A systematic review and meta-analysis. Urol J 19(1):1–8 Zanetti SP, Lievore E, Fontana M et al (2021) Vacuum-assisted mini-PNL: A new perspective in fragment clearance and pressure control. World J Urol 39(6):1717–1723. 10.1007/s00345-020-03318-5 Tables Table 1. Comparison of demographic, perioperative, and postoperative parameters across PNL groups Variable Standard PNL (n=40) Mini PNL (n=40) Micro PNL (n=20) Total (n=100) Age (years) 52.5 ± 11.9 (53.3) 52.6 ± 12.6 (53.2) 50.5 ± 9.9 (49.6) 52.2 ± 11.8 (52.6) Sex Male 31 (77.5%) 23 (52.5%) 10 (50%) 64 (64%) Female 9 (22.5%) 17 (47.5%) 10 (50%) 36 (36%) Comorbidity 8 (12.5%) 12 (30%) 5 (25%) 25 (25%) History of urologic surgery None 23 (57.5%) 23 (57.5%) 7 (35%) 53 (53%) URS 9 (22.5%) 14 (35%) 12 (60%) 35 (35%) PNL 8 (20%) 3 (7.5%) 1 (5%) 12 (12%) Renal anomaly 1 (2.6%) 0 1 (5%) 2 (2%) Degree of hydronephrosis Grade 0 1 (2.5%) 0 0 1 (1%) Grade 1 25 (62.5%) 12 (30%) 16 (80%) 53 (53%) Grade 2 11 (27.5%) 27 (67.5%) 4 (20%) 42 (42%) Grade 3 2 (5%) 1 (2.5%) 0 3 (3%) Grade 4 1 (2.5%) 0 0 1 (1%) Stone location Renal pelvis 27 (67.5%) 27 (67.5%) 12 (60%) 66 (66%) Upper calyx 2 (5%) 1 (2.5%) 1 (5%) 4 (4%) Middle calyx 5 (12.5%) 5 (12.5%) 2 (10%) 12 (12%) Lower calyx 6 (15%) 7 (17.5%) 5 (25%) 18 (18%) Stone size (mm) 28.6 ± 8.8 (27) 25.5 ± 8.7 (23) 17.5 ± 4.2 (17) 25.2 ± 8.96 (23) Stone volume (mm³) 4567 ± 3252 (3640) 2299.3 ± 1701.4 (1744.5) 1629.5 ± 808.4 (1427.5) 3072.3 ± 2644.9 (2255.5) Stone density (HU) 877.3 ± 390.7 (1012.5) 802.1 ± 394.1 (678) 866.4 ± 432.1 (757) 845.1 ± 398 (757) Access site Upper calyx 0 0 1 (5%) 1 (1%) Middle calyx 5 (12.5%) 13 (32.5%) 3 (15%) 21 (21%) Lower calyx 35 (87.5%) 27 (67.5%) 16 (80%) 78 (78%) Number of accesses 1.05 ± 0.2 (1) 1.05 ± 0.2 (1) 1 ± 0 (1) 1.04 ± 0.2 (1) Preoperative GFR (mL/min/1.73m²) 92.7 ± 19.6 (94.5) 89.8 ± 6.1 (91) 89.3 ± 8.2 (89.5) 90.9 ± 13.4 (92) Preoperative BUN (mg/dL) 15.4 ± 4 (14.5) 14.4 ± 5.3 (13) 14.4 ± 3.5 (14) 14.8 ± 4.5 (14) Preoperative creatinine (mg/dL) 0.9 ± 0.2 (0.88) 0.93 ± 0.38 (0.91) 0.86 ± 0.21 (0.84) 0.91 ± 0.28 (0.89) Preoperative hemoglobin (g/dL) 15.4 ± 1.8 (15.5) 15.2 ± 1.9 (15.6) 15.2 ± 1.7 (15.5) 15.3 ± 1.8 (15.5) Table 2. Comparison of patients with and without postoperative complications Variable No Complication (n=83) Complication (n=17) Grade 1 (n=11) Grade 2 (n=6) Total (n=100) Age (years) 51.4 ± 11.7 (52.3) 57.9 ± 12.2 (57) 52.6 ± 10.2 (56.4) 56 ± 11.5 (57) - Sex Male 53 (63.9%) 11 (64.7%) 6 (54.5%) 5 (83.3%) 64 (64%) Female 30 (36.1%) 6 (35.3%) 5 (45.5%) 1 (16.7%) 36 (36%) Comorbidity 22 (26.5%) 3 (17.6%) 1 (9.1%) 2 (33.3%) 25 (25%) History of Urologic Surgery None 42 (50.6%) 11 (64.7%) 7 (63.6%) 4 (66.7%) 53 (53%) URS 32 (38.6%) 3 (17.6%) 2 (18.2%) 1 (16.7%) 35 (35%) PNL 9 (10.8%) 3 (17.6%) 2 (18.2%) 1 (16.7%) 12 (12%) Renal anomaly 1 (1.2%) 1 (5.9%) 1 (10%) 0 2 (2%) Hydronephrosis grade Grade 0 1 (1.2%) 0 0 0 1 (1%) Grade 1 45 (54.2%) 8 (47.1%) 5 (45.5%) 3 (50%) 53 (53%) Grade 2 33 (39.8%) 9 (52.9%) 6 (54.5%) 3 (50%) 42 (42%) Stone location Renal pelvis 57 (68.7%) 11 (64.7%) 7 (63.6%) 4 (66.7%) 66 (66%) Upper calyx 1 (1.2%) 0 0 0 4 (4%) Middle calyx 10 (12%) 2 (11.8%) 0 2 (33.3%) 12 (12%) Lower calyx 15 (18.1%) 4 (23.5%) 4 (36.4%) 0 18 (18%) Stone size (mm) 24.2 ± 8.3 (23) 29.9 ± 10.6 (30) 28.3 ± 9.2 (30) 32.8 ± 13.3 (31) - Stone volume (mm³) 2953.8 ± 2583 (2036) 3651 ± 2943.5 (3026) 3300.2 ± 2387.6 (3025) 4294.2 ± 3944.2 (3600) - Stone density (HU) 888.1 ± 401.2 (910) 634.8 ± 314.1 (490) 615.8 ± 272.1 (490) 669.7 ± 406.6 (677.5) - Preoperative GFR 92.4 ± 12.7 (93) 83.5 ± 14.7 (86) 83.1 ± 17.1 (88) 84.2 ± 10.4 (85.5) - Preoperative BUN 14.5 ± 4.4 (13) 16 ± 4.6 (16) 16.3 ± 4.8 (16) 15.5 ± 4.7 (14) - Preoperative creatinine 0.9 ± 0.3 (0.86) 0.96 ± 0.22 (0.97) 0.96 ± 0.3 (0.96) 0.97 ± 0.14 (1.02) - Preoperative hemoglobin 15.4 ± 1.8 (15.6) 14.8 ± 1.6 (15.1) 14.7 ± 1.5 (14.7) 15 ± 1.8 (15.7) - Table 3. Logistic regression analysis of predictors for postoperative complications Variable Univariate OR 95% CI p-value Multivariate OR 95% CI p-value Age 1.036 0.989–1.085 0.139 - - - Sex (female) 0.964 0.324–2.869 0.947 - - - Comorbidity 0.594 0.156–2.266 0.446 - - - History of urologic surgery 0.856 0.394–1.857 0.693 - - - Hydronephrosis grade 1.094 0.480–2.491 0.831 - - - Stone size 1.069 1.010–1.131 0.022 - - - Stone volume 1.000 1.000–1.000 0.328 - - - Stone density (HU) 0.998 0.997–1.000 0.022 0.997 0.994–0.999 0.006 Number of accesses 5.400 0.705–41.360 0.104 - - - Preoperative GFR 0.95 0.911–0.991 0.017 - - - Preoperative BUN 1.072 0.960–1.197 0.219 - - - Preoperative creatinine 1.948 0.402–9.447 0.408 - - - Preoperative hemoglobin 0.837 0.627–1.117 0.227 - - - ASA score 0.562 0.187–1.688 0.304 - - - Preoperative VAS 0.89 0.462–1.715 0.728 - - - Operation time 1.004 0.985–1.023 0.678 - - - Fluoroscopy time 1.008 0.992–1.024 0.338 - - - Puncture time 0.987 0.941–1.035 0.582 - - - Lithotripsy time 0.977 0.931–1.026 0.352 - - - Stone extraction time 1.077 0.960–1.209 0.207 - - - Forceps/Basket usage 1.02 0.974–1.068 0.398 - - - Estimated blood loss 1.003 0.993–1.013 0.596 - - - Irrigation volume 1.000 1.000–1.000 0.527 - - - Guy’s stone score 12.415 3.13–49.247 <0.001 53.360 5.593–590.08 0.001 CROES score 1.001 0.992–1.010 0.834 - - - STONE score 1.597 0.791–3.226 0.191 - - - Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6973091","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":477480578,"identity":"e2135f2e-e41f-4e6e-b117-10fff807e65a","order_by":0,"name":"Hüseyin Biçer","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA8ElEQVRIiWNgGAWjYDCCAzxgiodBgrEBSNswMEiQqCWNeC0wlYcJa+G7ffaY5I+KwzLm0s2NHz7uOZ/YP7v54AOGGptoXFokz+WlSfOcOcxjOedgs+SMZ7cTZ9w5lmzAcCwttwGHFoMzPGbSjG2HeQxuJLYx8xy4ndhwI8cM6K/DeLVI/vwH1fLnwLnE+cRokeBtgGphOHAgcQMhLZJneIyteY6l8xjcAfql50Cy8cYbackGCXj8wneGx/Dmjxpre4Pb7Q8//DhgJzvvRvLBBx9qbHBqgYJmOMsRrDIBv3IQqIOz7AkrHgWjYBSMgpEGAE/0YhkIUlc3AAAAAElFTkSuQmCC","orcid":"","institution":"Kayseri City Hospital, University of Health Sciences","correspondingAuthor":true,"prefix":"","firstName":"Hüseyin","middleName":"","lastName":"Biçer","suffix":""},{"id":477480579,"identity":"c8011f80-4fa2-44f6-9ba9-02fdd8c1aa9f","order_by":1,"name":"Ömer Şahin","email":"","orcid":"","institution":"Kayseri City Hospital, University of Health Sciences","correspondingAuthor":false,"prefix":"","firstName":"Ömer","middleName":"","lastName":"Şahin","suffix":""},{"id":477480580,"identity":"bfc43774-a9e1-419b-b4bb-a30fdb73ce8a","order_by":2,"name":"Burak Elmaağaç","email":"","orcid":"","institution":"Kayseri City Hospital, University of Health Sciences","correspondingAuthor":false,"prefix":"","firstName":"Burak","middleName":"","lastName":"Elmaağaç","suffix":""},{"id":477480582,"identity":"e741b7b4-e970-429b-b669-31f20ef2b914","order_by":3,"name":"Abdullah Golbasi","email":"","orcid":"","institution":"Kayseri City Hospital, University of Health Sciences","correspondingAuthor":false,"prefix":"","firstName":"Abdullah","middleName":"","lastName":"Golbasi","suffix":""},{"id":477480583,"identity":"b7e2960f-83e3-4fe2-b919-97027352415e","order_by":4,"name":"Mert Ali Karadag","email":"","orcid":"","institution":"Kayseri City Hospital, University of Health Sciences","correspondingAuthor":false,"prefix":"","firstName":"Mert","middleName":"Ali","lastName":"Karadag","suffix":""}],"badges":[],"createdAt":"2025-06-25 09:38:33","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6973091/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6973091/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":86571067,"identity":"4716947c-b9ba-48d6-9a6b-06b0f62a6a01","added_by":"auto","created_at":"2025-07-12 14:16:46","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1204837,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6973091/v1/51b2f0df-4ff8-4b8d-801e-445c05bdda28.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Reducing Major Complications in Percutaneous Nephrolithotomy Through Surgical Standardization: A Retrospective Evaluation of 100 Cases and Review of the Literature","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003ePercutaneous nephrolithotomy (PNL) is the first-line treatment for renal calculi exceeding 2 cm in diameter, staghorn stones, multiple stones, or cases where extracorporeal shock wave lithotripsy (ESWL) and flexible ureteroscopy (FURS) have failed [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Since its introduction by Fernstr\u0026ouml;m and Johansson in 1976, PNL has become an essential modality in the surgical management of complex nephrolithiasis [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The first clinical series was published in 1979, and since the 1990s, both the European Association of Urology (EAU) and the American Urological Association (AUA) have endorsed PNL as the preferred treatment for large renal stones [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDepending on the diameter of the access sheath used, PNL procedures are typically classified as standard PNL (24\u0026ndash;30 Fr), mini PNL (12\u0026ndash;22 Fr for standard mini, 10\u0026ndash;14 Fr for super mini, and 11\u0026ndash;13 Fr for ultra-mini), and micro PNL (approximately 4.8 Fr) [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAdvances in technology over the past decade have significantly enhanced procedural efficacy and safety. Innovations such as vacuum-assisted renal access sheaths and endoscopic vision-guided entry have contributed to improved outcomes and reduced complication rates.\u003c/p\u003e \u003cp\u003eDespite these developments, serious complications\u0026mdash;including hemorrhage, injury to adjacent organs, and infectious events\u0026mdash;remain potential risks during PNL. In a study by Kyriazis et al. (2015), reported complication rates ranged widely, from 4\u0026ndash;50%, reflecting the heterogeneity of practice and patient populations [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. To standardize complication reporting, Tefekli and colleagues proposed an adapted version of the Clavien-Dindo classification specific to PNL in 2007, dividing outcomes into minor (grades 1\u0026ndash;2) and major (grades 3\u0026ndash;5) complications [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn our institution, a structured surgical protocol has been implemented to reduce variability and enhance procedural safety. By sharing the outcomes of the first 100 consecutive cases performed with micro, mini, and standard PNL techniques, we aim to contribute to the growing body of evidence supporting standardized strategies to mitigate perioperative risk in PNL.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cp\u003eThis retrospective observational study was conducted in accordance with the ethical principles of the Declaration of Helsinki and was approved by the Institutional Review Board of Kayseri City Training and Research Hospital (Approval No: 2024/116, dated May 14, 2024). Data were collected from patients who underwent percutaneous nephrolithotomy (PNL) between April 2022 and January 2024 due to renal calculi. All procedures were performed by a single high-volume endourologist(1000 PNL procedure with 15 years exprecience).\u003c/p\u003e\n\u003cp\u003ePatients were categorized into three groups based on the type of PNL technique applied:\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eMicro PNL\u003c/li\u003e\n \u003cli\u003eMini PNL\u003c/li\u003e\n \u003cli\u003eStandard PNL\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eComprehensive evaluations were conducted for each group, comparing demographic characteristics, preoperative findings, intraoperative parameters, and postoperative outcomes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.1 Preoperative Assessment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe choice of surgical technique was based on stone location, size, volume, Hounsfield unit (HU) density, surgeon\u0026rsquo;s experience, and institutional resources. All patients underwent preoperative non-contrast computed tomography (CT) to evaluate stone burden, HU density, number of stones, skin-to-stone distance, renal anatomical anomalies, and presence of retrorenal organs.\u003c/p\u003e\n\u003cp\u003eComplex cases were further assessed with advanced imaging such as CT angiography or intravenous pyelography [7]. In cases of impaired renal function or cortical thinning, renal scintigraphy (DTPA or MAG-3) was performed [8]. Patients with severe cortical atrophy were managed with alternative treatment strategies.\u003c/p\u003e\n\u003cp\u003eNomograms such as the Guy\u0026rsquo;s, STONE, and CROES scoring systems were calculated preoperatively for each patient to estimate stone complexity and predict stone-free status. In addition, retrorenal organ positioning was evaluated via prone ultrasonography.\u003c/p\u003e\n\u003cp\u003eSystemic comorbidities (e.g., diabetes mellitus, coronary artery disease, COPD), medication use, age, sex, body mass index (BMI), and spinal deformities were thoroughly reviewed for preoperative risk stratification. Surgical positioning was selected accordingly.\u003c/p\u003e\n\u003cp\u003eBaseline laboratory parameters\u0026mdash;complete blood count, serum creatinine, BUN, C-reactive protein (CRP), coagulation profile, and urinalysis\u0026mdash;were obtained for all patients. Those receiving antiplatelet or anticoagulant therapy underwent preoperative cardiology consultation.\u003c/p\u003e\n\u003cp\u003ePatients were operated on only after obtaining sterile urine cultures. Prophylactic intravenous administration of a third-generation cephalosporin was performed 30 minutes before the procedure.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 Intraoperative Technique\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAnesthetic strategy was individualized based on patient status, position, and expected surgical duration. Modified prone split-leg positioning was routinely preferred for its advantages in renal access and simultaneous retrograde intervention. Silicon pads were used to optimize pulmonary ventilation, and careful arm positioning was ensured to avoid brachial plexus injury.\u003c/p\u003e\n\u003cp\u003ePercutaneous access was guided by fluoroscopy, with an entry angle of 30\u0026deg; targeting the fornix and Brodel\u0026rsquo;s line to minimize bleeding risk. In suitable cases, endoscopic vision-guided access was performed to reduce fluoroscopy time and enhance safety.\u003c/p\u003e\n\u003cp\u003eUpper pole punctures were conducted under tidal volume control in coordination with the anesthesia team to avoid pleural injury. Lower calyx access was generally preferred. A flexible nephroscope or ureterorenoscope was used to reduce trauma and improve visualization.\u003c/p\u003e\n\u003cp\u003eDuring tract dilation, guidewire position was intermittently checked to prevent kinking or misplacement. Pneumatic or laser lithotripsy was performed under direct visualization, ensuring no injury to the collecting system.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3 Standardized Surgical Protocol for All PNL Modalities\u003c/strong\u003e\u003c/p\u003e\n\u003col start=\"1\" type=\"1\"\u003e\n \u003cli\u003eLithotomy positioning under general anesthesia.\u003c/li\u003e\n \u003cli\u003ePlacement of access sheath or ureteral catheter (5\u0026ndash;6 Fr) or vacuum-assisted ureteral sheath (9.5\u0026ndash;11 Fr).\u003cul type=\"circle\"\u003e\n \u003cli\u003eIn micro-PNL, if vacuum sheath insertion failed, a 6 Fr JJ stent was placed and the operation was postponed for two weeks.\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/li\u003e\n \u003cli\u003eTransition to prone split-leg position with repeated sterile draping.\u003c/li\u003e\n \u003cli\u003eIrrigation was maintained by gravity at ~1.5 meters above the patient using room temperature saline to control renal pelvic pressure.\u003c/li\u003e\n \u003cli\u003eFluoroscopy-guided puncture and tract dilation were carried out for standard and mini-PNL using appropriate access needles and Amplatz dilators.\u003c/li\u003e\n \u003cli\u003eInstrumentation and energy modalities varied by PNL technique (detailed below).\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003e\u003cstrong\u003e2.4 Surgical Equipment and Techniques\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStandard PNL\u003c/strong\u003e\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eDilation System:\u003c/strong\u003e 30 Fr Amplatz renal dilator (Cook Medical\u0026trade;)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAccess Sheath:\u003c/strong\u003e 30 Fr Amplatz renal sheath (Cook Medical\u0026trade;)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eNephroscope:\u003c/strong\u003e 24 Fr rigid nephroscope (Karl Storz\u0026trade;)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eEnergy Source:\u003c/strong\u003e EMS Swiss LithoClast\u0026reg; Master pneumatic lithotripter or 35 Watt Ho:YAG laser (Quanta System\u0026trade;, 550 \u0026micro;m fiber)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAdditional Instruments:\u003c/strong\u003e 16 Fr, 30 cm Malecot re-entry catheter or 6 Fr, 26 cm double-J ureteral stent (Plasti-med\u0026trade;)\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eMini PNL\u003c/strong\u003e\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eDilation System:\u003c/strong\u003e 16 Fr Amplatz renal dilator (single-shot technique, Cook Medical\u0026trade;)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAccess Sheath:\u003c/strong\u003e 16 Fr ClearPetra\u0026reg; vacuum-assisted sheath (Well Lead Medical\u0026trade;)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eNephroscope:\u003c/strong\u003e 12 Fr mini-nephroscope (Karl Storz\u0026trade;)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eEnergy Source:\u003c/strong\u003e 35 Watt Ho:YAG laser (Quanta System\u0026trade;, 550 \u0026micro;m fiber)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAdditional Instruments:\u003c/strong\u003e 6 Fr ureteral catheter or 6 Fr, 26 cm double-J stent\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003eMicro PNL\u003c/strong\u003e\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eAccess Sheath:\u003c/strong\u003e Vacuum-assisted ureteral access sheath (connected to 200 mmHg suction)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eNephroscope:\u003c/strong\u003e 4.8 Fr \u0026ldquo;All-Seeing Needle\u0026rdquo; (Plasti-med\u0026trade;, 20 cm)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eEnergy Source:\u003c/strong\u003e 35 Watt Ho:YAG laser (Quanta System\u0026trade;, 272 \u0026micro;m fiber)\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAdditional Instruments:\u003c/strong\u003e 6 Fr ureteral catheter or 6 Fr, 26 cm double-J stent\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003e2.5 Postoperative Management\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo minimize postoperative complications, all patients underwent close hemodynamic monitoring during the early recovery phase. Intravenous fluid support was administered, and empiric antibiotic therapy was initiated in patients presenting with fever. Pharmacologic prophylaxis against venous thromboembolism was applied in selected cases.\u003c/p\u003e\n\u003cp\u003eVital signs\u0026mdash;including body temperature, heart rate, blood pressure, and respiratory rate\u0026mdash;were recorded at regular intervals. Urine output and color were carefully observed for any signs of bleeding. In patients presenting with macroscopic hematuria or hypotension, angiographic evaluation and potential embolization were considered.\u003c/p\u003e\n\u003cp\u003ePostoperative laboratory assessments included:\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eHemoglobin\u003c/li\u003e\n \u003cli\u003eBlood urea nitrogen (BUN)\u003c/li\u003e\n \u003cli\u003eSerum creatinine\u003c/li\u003e\n \u003cli\u003eC-reactive protein (CRP)\u003c/li\u003e\n \u003cli\u003eCoagulation parameters\u003c/li\u003e\n \u003cli\u003eWhite blood cell count\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eRadiological follow-up to assess residual stone fragments was conducted at postoperative day 30 using either non-contrast CT or plain kidney-ureter-bladder (KUB) radiography. Simultaneously, serum creatinine levels were reassessed to detect potential renal functional decline.\u003c/p\u003e\n\u003cp\u003eCatheters and drains were removed based on clinical stability:\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eThe Foley catheter was withdrawn on postoperative day 1.\u003c/li\u003e\n \u003cli\u003eRe-entry Malecot catheters were removed within 1\u0026ndash;2 days if no fever or significant hematuria was noted.\u003c/li\u003e\n \u003cli\u003eUreteral stents were extracted within 2\u0026ndash;3 weeks postoperatively.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003e2.6 Statistical Analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll statistical analyses were performed using SPSS version 25.0 (IBM Corp., Armonk, NY, USA). Continuous variables were expressed as mean \u0026plusmn; standard deviation and median values, while categorical variables were summarized as frequencies and percentages.\u003c/p\u003e\n\u003cp\u003eTo evaluate predictive factors for minor complications following PNL, logistic regression analysis was applied. Initially, univariate logistic regression was conducted to identify potential associations between preoperative and perioperative variables and postoperative complications. Variables with a p-value \u0026lt;0.05 in univariate analysis were further included in a multivariate logistic regression model to determine independent risk factors.\u003c/p\u003e\n\u003cp\u003eA p-value of less than 0.05 was considered statistically significant in all analyses.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003eA total of 100 patients underwent PNL procedures using standard (n=40), mini (n=40), or micro (n=20) techniques. Detailed demographic, perioperative, and postoperative data for each group are summarized in \u003cstrong\u003eTable 1\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003eNo major complications (Clavien-Dindo grades 3\u0026ndash;5) were observed in any of the procedures. Overall, 17 patients (17%) experienced minor complications. According to the Clavien-Dindo classification:\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eStandard PNL group:\u003c/strong\u003e\n \u003cul type=\"circle\"\u003e\n \u003cli\u003eGrade 1: 5 patients (fever n=3; transient rise in serum creatinine n=2)\u003c/li\u003e\n \u003cli\u003eGrade 2: 4 patients (blood transfusion n=2; early postoperative urinary leakage n=2)\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eMini PNL group:\u003c/strong\u003e\n \u003cul type=\"circle\"\u003e\n \u003cli\u003eGrade 1: 3 patients (fever n=2; transient creatinine elevation n=1)\u003c/li\u003e\n \u003cli\u003eGrade 2: 1 patient (blood transfusion)\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eMicro PNL group:\u003c/strong\u003e\n \u003cul type=\"circle\"\u003e\n \u003cli\u003eGrade 1: 3 patients (fever n=2; transient creatinine elevation n=1)\u003c/li\u003e\n \u003cli\u003eGrade 2: 1 patient (antibiotic-requiring urinary tract infection)\u003c/li\u003e\n \u003c/ul\u003e\n \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eNotably, no patient experienced grade 3 or higher complications across all PNL modalities.\u003c/p\u003e\n\u003cp\u003ePatients who developed complications had significantly larger stone size and volume, but lower stone density (HU) compared to those without complications. Furthermore, elevated preoperative BUN and creatinine levels, along with lower hemoglobin and estimated glomerular filtration rate (eGFR), were more frequently observed in the complication group.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e compares key demographic, clinical, and radiological parameters between patients with and without complications.\u003c/p\u003e\n\u003cp\u003eTo further investigate risk factors, logistic regression analysis was conducted. \u003cstrong\u003eUnivariate analysis\u003c/strong\u003e identified four variables significantly associated with increased risk of complications:\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eLarger stone size (p=0.022)\u003c/li\u003e\n \u003cli\u003eLower stone density (p=0.022)\u003c/li\u003e\n \u003cli\u003eDecreased preoperative eGFR (p=0.017)\u003c/li\u003e\n \u003cli\u003eHigher Guy\u0026rsquo;s stone score (p\u0026lt;0.001)\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eIn \u003cstrong\u003emultivariate analysis\u003c/strong\u003e, two independent predictors of minor postoperative complications were identified:\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003eDecreased stone density (OR: 0.997; 95% CI: 0.994\u0026ndash;0.999; p=0.006)\u003c/li\u003e\n \u003cli\u003eElevated Guy\u0026rsquo;s stone score (OR: 53.360; 95% CI: 5.593\u0026ndash;590.08; p=0.001)\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThese findings are presented in \u003cstrong\u003eTable 3\u003c/strong\u003e.\u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cp\u003ePercutaneous nephrolithotomy (PNL) has been the cornerstone surgical approach for managing renal calculi larger than 2 cm, multiple stones, staghorn calculi, or those refractory to ESWL or flexible ureteroscopy (FURS).\u003csup\u003e1\u003c/sup\u003e Despite being widely accepted and refined over decades, PNL remains technically demanding, associated with a steep learning curve and a risk of significant complications\u0026mdash;particularly when performed by less experienced surgeons [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBoth the European Association of Urology (EAU) and the American Urological Association (AUA) continue to endorse PNL as a first-line treatment for large renal stones. In addition, PNL is increasingly used in select cases such as symptomatic calyceal diverticular stones, failed FURS, and patients with urinary diversions or anatomical anomalies [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis study provides compelling evidence that surgical standardization can significantly reduce the rate of major complications during PNL. In our series of 100 consecutive cases, no Clavien-Dindo grade 3\u0026ndash;5 complications were observed. These results contrast with existing literature, where complication rates after PNL vary between 8.1% and 19.6% depending on patient and procedural factors [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. In a meta-analysis involving nearly 12,000 cases, reported complication rates were: fever (10.8%), transfusion (7%), thoracic complications (1.5%), sepsis (0.5%), visceral injury (0.4%), embolization (0.4%), urinoma (0.2%), and mortality (0.05%) [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe use of a modified Clavien-Dindo classification specific to PNL has enabled a more granular understanding of perioperative risks [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. According to Seitz et al., Grade 1\u0026ndash;2 events (%95.1) account for the majority of complications, while Grade\u0026thinsp;\u0026ge;\u0026thinsp;3 events (%4.9) are rare but clinically significant [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cb\u003eHemorrhagic Complications\u003c/b\u003e \u003c/p\u003e \u003cp\u003eBleeding remains one of the most serious complications of PNL, ranging from mild hematuria to life-threatening hemorrhage requiring embolization [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Risk factors include solitary kidney, multiple tracts, large stone burden, prolonged operative time, active infection, and diabetes mellitus [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn our series, the mean hemoglobin drop was 0.99\u0026thinsp;\u0026plusmn;\u0026thinsp;1.04 g/dL, and the transfusion rate was only 4%, notably lower than the 7% reported in literat\u0026uuml;re [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWe attribute this favorable outcome to our standardized surgical strategy:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003ePre-access planning based on CT measurements to avoid vascular injury\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eNeedle insertion targeting Brodel\u0026rsquo;s line\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eControlled dilation under direct endoscopic and fluoroscopic guidance\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eAvoidance of excessive torque during nephroscopy\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eInfectious Complications\u003c/b\u003e \u003c/p\u003e \u003cp\u003eFever occurred in 10% of cases, while urinary tract infections requiring antibiotics occurred in 2%. No cases of sepsis or septic shock were observed. This is significantly lower than previously reported rates ranging from 4.3\u0026ndash;12.8% [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Key measures likely contributing to this outcome include:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eEnsuring negative preoperative urine culture\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eUse of vacuum-assisted sheaths to reduce intrarenal pressure\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eCollection of renal pelvic and stone cultures during surgery\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003ePostponement of procedures with pyuric aspirates until proper antibiotic therapy was initiated\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eTailored postoperative antibiotic regimens based on intraoperative culture results\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eVacuum-assisted access systems have been shown to maintain renal pelvic pressures below 6 cm H₂O, as opposed to pressures exceeding 100 cm H₂O with conventional mini-PNL sheaths [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Several studies including those by Zanetti et al. have reported reduced operative time and lower infection rates with these systems [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cb\u003eVisceral Injury\u003c/b\u003e \u003c/p\u003e \u003cp\u003eNo visceral organ injuries were encountered in our series. This may be attributed to preoperative evaluation of adjacent anatomy using CT and prone ultrasound, and the use of flexible nephroscopes to access upper pole stones rather than supracostal puncture. According to the literature, pleural injuries occur in ~\u0026thinsp;1.5% and colonic injuries in ~\u0026thinsp;0.4% of cases [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eImportantly, none of the major complications defined by Tefekli et al. such as urinoma requiring stenting, pneumothorax, embolization, perinephric abscess, or nephrectomy\u0026mdash;were observed in our cohort [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cb\u003eProtocol-Based Surgery: A Reproducible Model\u003c/b\u003e \u003c/p\u003e \u003cp\u003ePerhaps the most important implication of our findings is the feasibility and effectiveness of a reproducible, checklist-driven surgical model for PNL. While most complications are multifactorial, we show that when the operative sequence is optimized and protocolized, adverse outcomes can be minimized regardless of the PNL subtype.\u003c/p\u003e \u003cp\u003eThis approach mirrors developments in other surgical disciplines, such as enhanced recovery after surgery (ERAS) protocols, and is consistent with the trend toward standardization in urologic oncology and reconstruction. For endourology to continue evolving, surgical reproducibility and safety should be as emphasized as efficacy.\u003c/p\u003e"},{"header":"5. Limitations","content":"\u003cp\u003eThis study has several limitations that must be acknowledged:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eRetrospective design\u003c/b\u003e: The non-randomized and retrospective nature of the study precludes strong causal inference and may introduce selection bias.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eSingle-center, single-surgeon data\u003c/b\u003e: While ensuring procedural consistency, this limits generalizability to broader clinical environments with varying surgical expertise and institutional protocols.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eSample size\u003c/b\u003e: Although 100 patients were included, the cohort may be underpowered to detect rare complications or to fully compare subgroups stratified by surgical technique.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eShort-term follow-up\u003c/b\u003e: The study lacked long-term postoperative surveillance, which prevents assessment of delayed complications, such as ureteral strictures, recurrent stone formation, or chronic renal impairment.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e"},{"header":"6. Conclusion","content":"\u003cp\u003eOur findings demonstrate that implementing standardized surgical protocols\u0026mdash;encompassing preoperative imaging-based planning, sterile urine control, optimized patient positioning, intraoperative pressure regulation using vacuum-assisted systems, and vigilant postoperative monitoring\u0026mdash;can significantly reduce the risk of major complications in PNL procedures.\u003c/p\u003e \u003cp\u003eThe absence of Clavien-Dindo grade 3\u0026ndash;5 events in our 100-patient cohort underscores the potential of protocol-driven interventions to enhance procedural safety. These results provide practical insight for urologic surgeons aiming to minimize perioperative risk and support the development of reproducible, low-complication clinical pathways in endourology.\u003c/p\u003e \u003cp\u003eFuture multicenter and prospective studies are warranted to validate these findings across different practice settings and to further refine PNL safety standards.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no conflicts of interest relevant to this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research received no external funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted in accordance with the principles of the Declaration of Helsinki and was approved by the Institutional Review Board of Kayseri City Training and Research Hospital (Approval No: 2024/116; Date: May 14, 2024).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eH\u0026uuml;seyin Bi\u0026ccedil;er: Conceptualization, Methodology, Surgery, Writing \u0026ndash; original draft\u003cbr\u003e\u0026Ouml;mer Şahin: Data curation, Formal analysis\u003cbr\u003eBurak Elmaağa\u0026ccedil;: Visualization, Literature review\u003cbr\u003eAbdullah G\u0026ouml;lbaşı: Investigation, Data interpretation\u003cbr\u003eMert Ali Karadağ: Statistical analysis, Editing\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eRamakumar S, Segura JW (2000) Renal calculi. Percutaneous management. Urol Clin North Am 27(4):617\u0026ndash;622\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFernstrom I, Johansson B (1976) Percutaneous pyelolithotomy: A new extraction technique. Scand J Urol Nephrol 10(3):257\u0026ndash;259\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZeng G, Cai C, Duan X et al (2021) Mini percutaneous nephrolithotomy is a noninferior modality to standard percutaneous nephrolithotomy for the management of 20\u0026ndash;40 mm renal calculi: A multicenter randomized controlled trial. Eur Urol 79(1):114\u0026ndash;121. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.eururo.2020.09.026\u003c/span\u003e\u003cspan address=\"10.1016/j.eururo.2020.09.026\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTzelves L, Skolarikos A (2020) Suction use during endourological procedures. 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Exp Ther Med 21(3):213\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSeitz C, Desai M, H\u0026auml;cker A et al (2012) Incidence, prevention, and management of complications following percutaneous nephrolitholapaxy. Eur Urol 61(1):146\u0026ndash;158\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFeng D, Hu X, Tang Y et al (2020) Miniaturized versus standard percutaneous nephrolithotomy: A systematic review and meta-analysis of RCTs. Investig Clin Urol 61(2):115\u0026ndash;126\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSacha K, Szewczyk W, Bar K (1996) Massive hemorrhage as a complication after percutaneous nephrolithotomy. Int Urol Nephrol 28(3):315\u0026ndash;318\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRichstone L, Reggio E, Ost MC et al (2008) Hemorrhage following percutaneous renal surgery: Characterization of angiographic findings. J Endourol 22(6):1129\u0026ndash;1135\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAkman T, Binbay M, Sari E et al (2011) Factors affecting bleeding during percutaneous nephrolithotomy: A single surgeon\u0026rsquo;s experience. J Endourol 25(2):327\u0026ndash;333\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRivera M, Viers B, Cockerill P et al (2016) Pre- and postoperative predictors of infection-related complications in patients undergoing percutaneous nephrolithotomy. J Endourol 30(9):982\u0026ndash;986\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNagele U, Horstmann M, Sievert KD et al (2007) A newly designed amplatz sheath decreases intrapelvic pressure during mini-perc: In-vitro study. J Endourol 21(10):1113\u0026ndash;1116\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang Z, Song L, Xie D et al (2016) Mini-PCNL with suctioning device: Efficient and safe management of staghorn calculi. Urol Int 97(1):61\u0026ndash;66\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen D, Chen C, Xie Y et al (2021) Suctioning vs. traditional sheath in mini-PNL: A systematic review and meta-analysis. Urol J 19(1):1\u0026ndash;8\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZanetti SP, Lievore E, Fontana M et al (2021) Vacuum-assisted mini-PNL: A new perspective in fragment clearance and pressure control. World J Urol 39(6):1717\u0026ndash;1723. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00345-020-03318-5\u003c/span\u003e\u003cspan address=\"10.1007/s00345-020-03318-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1. Comparison of demographic, perioperative, and postoperative parameters across PNL groups\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eStandard PNL (n=40)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eMini PNL (n=40)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eMicro PNL (n=20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eTotal (n=100)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e52.5 \u0026plusmn; 11.9 (53.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e52.6 \u0026plusmn; 12.6 (53.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e50.5 \u0026plusmn; 9.9 (49.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e52.2 \u0026plusmn; 11.8 (52.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eSex\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Male\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e31 (77.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e23 (52.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e10 (50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e64 (64%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Female\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e9 (22.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e17 (47.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e10 (50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e36 (36%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eComorbidity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e8 (12.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e12 (30%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e5 (25%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e25 (25%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eHistory of urologic surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; None\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e23 (57.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e23 (57.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e7 (35%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e53 (53%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; URS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e9 (22.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e14 (35%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e12 (60%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e35 (35%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; PNL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e8 (20%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e3 (7.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e12 (12%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eRenal anomaly\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (2.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e2 (2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eDegree of hydronephrosis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Grade 0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (2.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Grade 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e25 (62.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e12 (30%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e16 (80%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e53 (53%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Grade 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e11 (27.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e27 (67.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e4 (20%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e42 (42%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Grade 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e2 (5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (2.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e3 (3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Grade 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (2.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eStone location\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Renal pelvis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e27 (67.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e27 (67.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e12 (60%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e66 (66%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Upper calyx\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e2 (5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (2.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e4 (4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Middle calyx\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e5 (12.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e5 (12.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e2 (10%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e12 (12%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Lower calyx\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e6 (15%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e7 (17.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e5 (25%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e18 (18%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eStone size (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e28.6 \u0026plusmn; 8.8 (27)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e25.5 \u0026plusmn; 8.7 (23)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e17.5 \u0026plusmn; 4.2 (17)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e25.2 \u0026plusmn; 8.96 (23)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eStone volume (mm\u0026sup3;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e4567 \u0026plusmn; 3252 (3640)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e2299.3 \u0026plusmn; 1701.4 (1744.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1629.5 \u0026plusmn; 808.4 (1427.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e3072.3 \u0026plusmn; 2644.9 (2255.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eStone density (HU)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e877.3 \u0026plusmn; 390.7 (1012.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e802.1 \u0026plusmn; 394.1 (678)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e866.4 \u0026plusmn; 432.1 (757)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e845.1 \u0026plusmn; 398 (757)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eAccess site\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Upper calyx\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 (1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Middle calyx\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e5 (12.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e13 (32.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e3 (15%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e21 (21%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e\u0026nbsp; Lower calyx\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e35 (87.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e27 (67.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e16 (80%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e78 (78%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003eNumber of accesses\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1.05 \u0026plusmn; 0.2 (1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1.05 \u0026plusmn; 0.2 (1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1 \u0026plusmn; 0 (1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e1.04 \u0026plusmn; 0.2 (1)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003ePreoperative GFR (mL/min/1.73m\u0026sup2;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e92.7 \u0026plusmn; 19.6 (94.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e89.8 \u0026plusmn; 6.1 (91)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e89.3 \u0026plusmn; 8.2 (89.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e90.9 \u0026plusmn; 13.4 (92)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003ePreoperative BUN (mg/dL)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e15.4 \u0026plusmn; 4 (14.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e14.4 \u0026plusmn; 5.3 (13)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e14.4 \u0026plusmn; 3.5 (14)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e14.8 \u0026plusmn; 4.5 (14)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003ePreoperative creatinine (mg/dL)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0.9 \u0026plusmn; 0.2 (0.88)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0.93 \u0026plusmn; 0.38 (0.91)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0.86 \u0026plusmn; 0.21 (0.84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e0.91 \u0026plusmn; 0.28 (0.89)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003ePreoperative hemoglobin (g/dL)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e15.4 \u0026plusmn; 1.8 (15.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e15.2 \u0026plusmn; 1.9 (15.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e15.2 \u0026plusmn; 1.7 (15.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 115px;\"\u003e\n \u003cp\u003e15.3 \u0026plusmn; 1.8 (15.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2. Comparison of patients with and without postoperative complications\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eNo Complication (n=83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eComplication (n=17)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eGrade 1 (n=11)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eGrade 2 (n=6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eTotal (n=100)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e51.4 \u0026plusmn; 11.7 (52.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e57.9 \u0026plusmn; 12.2 (57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e52.6 \u0026plusmn; 10.2 (56.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e56 \u0026plusmn; 11.5 (57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eSex\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; Male\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e53 (63.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e11 (64.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e6 (54.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e5 (83.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e64 (64%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; Female\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e30 (36.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e6 (35.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e5 (45.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e1 (16.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e36 (36%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eComorbidity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e22 (26.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e3 (17.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e1 (9.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e2 (33.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e25 (25%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eHistory of Urologic Surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; None\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e42 (50.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e11 (64.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e7 (63.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e4 (66.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e53 (53%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; URS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e32 (38.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e3 (17.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e2 (18.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e1 (16.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e35 (35%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; PNL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e9 (10.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e3 (17.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e2 (18.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e1 (16.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e12 (12%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eRenal anomaly\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e1 (1.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e1 (5.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e1 (10%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e2 (2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eHydronephrosis grade\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; Grade 0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e1 (1.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e1 (1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; Grade 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e45 (54.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e8 (47.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e5 (45.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e3 (50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e53 (53%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; Grade 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e33 (39.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e9 (52.9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e6 (54.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e3 (50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e42 (42%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eStone location\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; Renal pelvis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e57 (68.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e11 (64.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e7 (63.6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e4 (66.7%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e66 (66%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; Upper calyx\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e1 (1.2%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e4 (4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; Middle calyx\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e10 (12%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e2 (11.8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e2 (33.3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e12 (12%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u0026nbsp; Lower calyx\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e15 (18.1%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e4 (23.5%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e4 (36.4%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e18 (18%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eStone size (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e24.2 \u0026plusmn; 8.3 (23)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e29.9 \u0026plusmn; 10.6 (30)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e28.3 \u0026plusmn; 9.2 (30)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e32.8 \u0026plusmn; 13.3 (31)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eStone volume (mm\u0026sup3;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e2953.8 \u0026plusmn; 2583 (2036)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e3651 \u0026plusmn; 2943.5 (3026)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e3300.2 \u0026plusmn; 2387.6 (3025)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e4294.2 \u0026plusmn; 3944.2 (3600)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eStone density (HU)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e888.1 \u0026plusmn; 401.2 (910)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e634.8 \u0026plusmn; 314.1 (490)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e615.8 \u0026plusmn; 272.1 (490)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e669.7 \u0026plusmn; 406.6 (677.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003ePreoperative GFR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e92.4 \u0026plusmn; 12.7 (93)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e83.5 \u0026plusmn; 14.7 (86)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e83.1 \u0026plusmn; 17.1 (88)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e84.2 \u0026plusmn; 10.4 (85.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003ePreoperative BUN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e14.5 \u0026plusmn; 4.4 (13)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e16 \u0026plusmn; 4.6 (16)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e16.3 \u0026plusmn; 4.8 (16)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e15.5 \u0026plusmn; 4.7 (14)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003ePreoperative creatinine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.9 \u0026plusmn; 0.3 (0.86)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.96 \u0026plusmn; 0.22 (0.97)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.96 \u0026plusmn; 0.3 (0.96)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.97 \u0026plusmn; 0.14 (1.02)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003ePreoperative hemoglobin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e15.4 \u0026plusmn; 1.8 (15.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e14.8 \u0026plusmn; 1.6 (15.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e14.7 \u0026plusmn; 1.5 (14.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e15 \u0026plusmn; 1.8 (15.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3. Logistic regression analysis of predictors for postoperative complications\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eUnivariate OR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eMultivariate OR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eAge\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.036\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.989\u0026ndash;1.085\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.139\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eSex (female)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.964\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.324\u0026ndash;2.869\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.947\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eComorbidity\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.594\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.156\u0026ndash;2.266\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.446\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eHistory of urologic surgery\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.856\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.394\u0026ndash;1.857\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.693\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eHydronephrosis grade\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.094\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.480\u0026ndash;2.491\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.831\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eStone size\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.069\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.010\u0026ndash;1.131\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.022\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eStone volume\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.000\u0026ndash;1.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.328\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eStone density (HU)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.998\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.997\u0026ndash;1.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.022\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.997\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.994\u0026ndash;0.999\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.006\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eNumber of accesses\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e5.400\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.705\u0026ndash;41.360\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.104\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003ePreoperative GFR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.911\u0026ndash;0.991\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.017\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003ePreoperative BUN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.072\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.960\u0026ndash;1.197\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.219\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003ePreoperative creatinine\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.948\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.402\u0026ndash;9.447\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.408\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003ePreoperative hemoglobin\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.837\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.627\u0026ndash;1.117\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.227\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eASA score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.562\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.187\u0026ndash;1.688\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.304\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003ePreoperative VAS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.462\u0026ndash;1.715\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.728\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eOperation time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.985\u0026ndash;1.023\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.678\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eFluoroscopy time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.008\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.992\u0026ndash;1.024\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.338\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003ePuncture time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.987\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.941\u0026ndash;1.035\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.582\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eLithotripsy time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.977\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.931\u0026ndash;1.026\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.352\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eStone extraction time\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.077\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.960\u0026ndash;1.209\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.207\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eForceps/Basket usage\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.974\u0026ndash;1.068\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.398\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eEstimated blood loss\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.993\u0026ndash;1.013\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.596\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eIrrigation volume\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.000\u0026ndash;1.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.527\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eGuy\u0026rsquo;s stone score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e12.415\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e3.13\u0026ndash;49.247\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e53.360\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e5.593\u0026ndash;590.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eCROES score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.992\u0026ndash;1.010\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.834\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003eSTONE score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e1.597\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.791\u0026ndash;3.226\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e0.191\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 82px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Percutaneous nephrolithotomy, surgical standardization, complication prevention, Clavien-Dindo classification, vacuum-assisted sheath, intrarenal pressure control, minimally invasive urologic surgery","lastPublishedDoi":"10.21203/rs.3.rs-6973091/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6973091/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eObjective:\u003c/strong\u003e\u003cbr\u003e\nThis study aims to assess the effectiveness of standardized preoperative, intraoperative, and postoperative protocols in preventing major complications (Clavien-Dindo grades 3–5) during percutaneous nephrolithotomy (PNL) procedures performed with micro, mini, and standard techniques in our clinic.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMaterials and Methods:\u003c/strong\u003e\u003cbr\u003e\nA total of 100 consecutive patients who underwent PNL for renal calculi between April 2022 and January 2024 were retrospectively evaluated. Surgical approaches included micro, mini, and standard PNL, all performed by a single experienced surgeon. Patient demographics, stone characteristics, procedural details, complications, and outcomes were systematically analyzed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e\u003cbr\u003e\nNo major complications were observed across all procedures. Standardized measures—such as careful selection of minimally invasive techniques, use of vacuum-assisted renal sheaths, preoperative sterile urine cultures, controlled intrarenal pressure, and intraoperative flexible endoscopic evaluation—were instrumental in reducing risk. Minor complications occurred in 11% of cases (grade 1) and 6% (grade 2). Logistic regression analysis identified lower stone density and higher Guy’s stone scores as independent predictors of postoperative complications.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e\u003cbr\u003e\nImplementing a comprehensive and standardized surgical protocol significantly minimized the incidence of major complications in PNL procedures. These findings suggest that clinical pathways emphasizing meticulous planning, imaging-based entry strategies, pressure control, and intraoperative assessments can substantially improve safety profiles. Multicenter prospective studies are warranted to further validate these outcomes.\u003c/p\u003e","manuscriptTitle":"Reducing Major Complications in Percutaneous Nephrolithotomy Through Surgical Standardization: A Retrospective Evaluation of 100 Cases and Review of the Literature","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-03 05:31:54","doi":"10.21203/rs.3.rs-6973091/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"890ca7c7-5595-4cb0-bf5f-c90016e066aa","owner":[],"postedDate":"July 3rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-12T14:08:28+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-03 05:31:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6973091","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6973091","identity":"rs-6973091","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}