The Critical Role of Calyceal Anatomy in Achieving Stone-Free Status After PCNL: A Prospective Study

The Critical Role of Calyceal Anatomy in Achieving Stone-Free Status After PCNL: A Prospective Study | 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 The Critical Role of Calyceal Anatomy in Achieving Stone-Free Status After PCNL: A Prospective Study Kartikesh Mishra, Ram Sagar Shah, Abhisekh Paudel This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9187056/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 Introduction: Percutaneous nephrolithotomy (PCNL) is the gold standard for large renal calculi.This study aimed to prospectively evaluate the impact of specific anatomical parameters, measured on retrograde pyelogram, on stone-free rates (SFR) and perioperative outcomes after PCNL. Methods: This prospective, observational study included 350 patients who underwent PCNL. Preoperative anatomical parameters—including calyx diameter, calyx-to-pelvis distance, infundibulopelvic angle (IPA), and maximum calyx-stone angle (max CSA) were measured on retrograde pyelograms. Outcomes assessed were SFR at 4 weeks, complications (Clavien-Dindo), and haemoglobin drop. Statistical analysis included ROC curve, univariate, and multivariate regression analyses. Results: The overall SFR was 91.7%. ROC analysis identified max CSA as the strongest anatomical predictor of SFR (AUC 0.722), with a cut-off of ≥ 72° (sensitivity 69.0%, specificity 74.5%). On multivariate analysis, tract length > 10 cm (p = 0.011) and GUY’S Score Grade 1 (p = 0.018) were independent predictors of SFR. Major complications (Clavien-Dindo ≥ 2) occurred in 7.4% and were independently predicted by stone density ≤ 950 HU (p = 0.001) and intraoperative bleeding (p = 0.006). A significant haemoglobin drop (≥ 1.95 g/dl) was independently associated with nephrostomy tube requirement (p = 0.032), higher hydronephrosis grade (p = 0.042), max CSA ≥ 72° (p = 0.008), and multiple tracts (p = 0.021). Conclusion: Calyceal anatomy, particularly the maximum calyx-stone angle, is a significant predictor of stone-free status after PCNL. Anatomical parameters also play a role in perioperative morbidity. Preoperative assessment of these factors can aid in surgical planning and patient counselling. Nephrolithotomy Kidney Calices Treatment Outcome Postoperative Complications Predictive Value of Tests Retrograde Pyelography Figures Figure 1 1. Introduction Percutaneous nephrolithotomy (PCNL) has been the gold-standard treatment for large renal calculi (> 2 cm) since its inception in the 1970s, establishing itself as a highly effective procedure with superior stone-free rates (SFRs) compared to shockwave lithotripsy (SWL) or retrograde intrarenal surgery (RIRS) for such stones ( 1 ). The fundamental procedure involves gaining percutaneous access into the collecting system, dilating the tract, and using endoscopic instruments to fragment and remove stones. Numerous patient-specific and stone-specific factors have been extensively studied and identified as predictors of these outcomes. Key among them are stone burden (size and volume), stone density (Hounsfield Units), stone location, patient comorbidities, and Body Mass Index (BMI) ( 2 ). The Guy’s Stone Score and the S.T.O.N.E. nephrolithometry score are examples of pre-operative grading systems that incorporate many of these factors to predict SFR ( 3 , 4 ). The renal collecting system is not a passive chamber but a complex, three-dimensional structure with significant anatomical variation. Key anatomical elements include the renal calyces, which are the chambers that collect urine; the infundibula, which are the narrow channels connecting the calyces to the renal pelvis; and the various angles formed between these structures. The initial step of obtaining optimal percutaneous access is arguably the most crucial, and it is profoundly influenced by the spatial orientation of the calyces and their relationship to the stone. Once access is established, the surgeon must manoeuvre the nephroscope through the infundibula to reach and clear all stone fragments. It is at this stage that anatomical constraints become critically important. A narrow, long, or acutely angled infundibulum can impede the passage of rigid scopes, limit irrigation flow, trap fragments, and complicate the use of lithotripters, potentially leading to incomplete stone clearance or increased risk of mucosal injury and bleeding ( 5 ). Traditional pre-operative planning, often based on two-dimensional imaging like intravenous urograms (IVU), fails to fully capture the spatial relationships. The intraoperative pyelogram provides an unprecedented opportunity to precisely measure these anatomical parameters. Therefore, a detailed investigation into specific anatomical metrics—such as calyceal location, diameter, infundibular dimensions, and critical angulations—is the necessary next step in refining patient selection, pre-operative planning, and prognostic prediction for PCNL. 2. Materials and Methods 2.1 Study Design and Setting This was a prospective, observational study conducted on consecutive patients undergoing PCNL between July 15, 2025, and December 15, 2025. Institutional ethical committee approval was obtained, and written informed consent was taken from all participants. 2.2 Participants All adult patients scheduled for PCNL were assessed for eligibility. The inclusion criteria were: ( 1 ) patients with renal stones > 2 cm in the pelvicalyceal system, and ( 2 ) patients with stones < 2 cm for whom PCNL was deemed the most appropriate intervention by the treating surgeon. Patients were excluded if they had: ( 1 ) uncorrected coagulopathy or were on anticoagulant therapy; ( 2 ) an active urinary tract infection or urosepsis at the time of surgery; ( 3 ) a known pregnancy; ( 4 ) incomplete data or were lost to follow-up; or ( 5 ) no preoperative computed tomography (CT) scan available for analysis. 2.3 Sample Size Calculation The sample size was calculated based on a similar study by Rathod et al. ( 6 ). Using a two-tailed alpha of 0.05 and 90% power, the required sample size was 25 patients per group. Accounting for a high success rate (86.67%) and a smaller failure group, the total sample size was estimated to be 188. To enhance the robustness of our findings, we enrolled 350 patients. 2.4. Measurements on retrograde pyelogram : Patients were initially placed in the lithotomy position for the cystoscopic placement of a 5–6 Fr ureteral catheter. Patients were then repositioned prone. Retrograde pyelogram was performed mostly with air (< 10ml) with gentle push and meglumine diatriazoate (76%) was used whenever it failed. A needle of 10ml syringe which measured 4.5cm in length was placed lateral to the spine of the patient in the prone position and retrograde contrast instillation was done in 0 degree C-ARM position. The retrograde pyelogram image was captured by an android mobile version 15AP3A.240905. 015.A2 with OS version 2.0.210.0. VNQINXM from the C-ARM monitor. ImageMeter version 3.9.10-1 (license: Free Evaluation) was used to perform measurements. In the ImageMeter application, previously placed needle which measured 4.5cm was take taken as reference scale. Calyx diameter was measured as distance between two furthest points on the circumference at the centre of the calyx. Calyx to pelvis distance was measured from the centre of the calyx to the centre of the pelvis. Infundibulopelvic angle (IPA) of the selected calyx was measured as the supplementary angle formed by the ureteric line and the calyx to pelvis line. Maximum Calyx to stone angle (max CSA) was defined as the angle formed by the calyx to pelvis line and the line joining the pelvis and lateral most calculus. This angle came out to be the sum of Infundibulopelvic angle and angle formed by the ureteric line and the line joining pelvis and lateral most calculus. As in the Fig. 1 , lateral most stone is present at point B in the lower calyx, thus maximum calyx to stone angle was angle COB = angle COU +angle UOB. Angle COU = angle AOU’ (vertically opposite angles) = Infundibulopelvic angle (IPA). Hence, maximum calyx to stone angle COB = IPA + angle UOB (angle formed by ureteric line and lateralmost calculus). In the Fig. 1 , IPA = 180 − 120=60, angle UOB = 75, thus max CSA = 60 + 75 = 135. Diameter of the infundibulum was judged preoperatively whether 18Fr amplatz sheath could be negotiated through the infundibulum or not. As presence of bleeding intraoperatively could affect stone free rate and predict major complication, it was noted and later analysed. Similarly, note regarding need of nephrostomy tube was made and its relationship with major complication was later analysed. 2.5 Data Collection and Outcome Measures Preoperative data included patient demographics, comorbidities, and stone characteristics (size, density, Guy's and STONE scores). Intraoperative data included calyceal measurements, number of access attempts, fluoroscopy time, and operative time. Postoperative outcomes assessed were: Stone-Free Rate (SFR) : Defined as the absence of any residual stone fragments > 4 mm on ultrasound imaging at 4 weeks post-procedure. Safety : All complications were recorded and graded according to the Clavien-Dindo (CD) classification system. Major complications were defined as CD Grade ≥ 2. Other parameters : Included drop in haemoglobin, need for blood transfusion, hospital stay, and requirement for secondary interventions. 2.6 Statistical Analysis Data were analysed using IBM SPSS version 26. Continuous variables were presented as mean ± standard deviation or median (range), and categorical variables as frequencies and percentages. ROC curve analysis was used to determine predictive cut-offs. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of outcomes. 3. Results 3.1 Patient Demographics and Baseline Characteristics A total of 350 patients were included. The baseline demographics and clinical characteristics are summarized in Table 1 . The median age was 40 years, with a slight male predominance (52.3%). The median STONE score was 7, and most patients had moderate (63.1%) or high (27.1%) complexity stones. The most frequently selected calyx for puncture was the upper compound calyx (56.0%). The median calyx diameter was 1.3 cm, median calyx-to-pelvis length was 3.5 cm, median IPA was 37 degrees, and median max CSA was 0 degrees. Table 1 Baseline demographics and clinical characteristics Parameter Subgroup / Finding Frequency (n) Percentage (%) Median (Range) Age (years) - - - 40 (2–87) Sex Male: Female 183: 167 Ratio: 1.09 - Comorbidities Hypertension (HTN) 36 10.3% - Diabetes Mellitus (DM) 24 6.9% - Other Comorbidity 18 5.1% - Surgical History History of ipsilateral PCNL 25 7.1% - History of ipsilateral open renal surgery 13 3.7% - Preoperative Labs Preoperative Hb (gm/dl) * - - 12.8 (8-18.5) Preoperative Cr (mg/dl) - - 0.9 (0.5–3.6) Stone Characteristics Stone Size (mm²) 1600 mm² 60 17.1% - Tract Length (cm) ≤ 10 cm 332 94.9% - > 10 cm 18 5.1% - Hydronephrosis Grade None or mild 275 78.6% - Moderate to severe 75 21.4% - Number of Calices Involved 1–2 266 76.0% - 3 25 7.1% - Staghorn 59 16.9% - Stone Density (HU) ≤ 950 HU 163 46.6% - > 950 HU 187 53.4% - Complexity Scores STONE Score Total Score - - 7 (5–13) Complexity Groups Low 34 9.7% - Moderate 221 63.1% - High 95 27.1% - GUY'S Score Grade 1 190 54.3% - Grade 2 91 26.0% - Grade 3 12 3.4% - Grade 4 57 16.3% - *Mean value Regarding the chosen calyx for puncture, the upper compound calyx was the most frequently selected, accounting for 56.0% (n = 196) of cases, followed by the middle posterior calyx in 32.0% (n = 112). The remaining punctures were distributed among the middle anterior (1.1%, n = 4), lower posterior (6.9%, n = 24), and lower compound calyces (4.0%, n = 14). The median calyx diameter was 1.3 cm (range: 0.4–6 cm), while the median calyx-to-pelvis length was 3.5 cm (range: 0.8–7.9 cm). The median infundibulopelvic angle was 37 degrees (range: 0–140 degrees), and the median maximum calyx-stone angle was 0 degrees (range: 0–180 degrees). The infundibular diameter of the selected calyx was greater than 18 Fr in most patients (94.9%, n = 332). The stone-free rate at four weeks was 91.7%, with 321 patients (91.7%) demonstrating no residual stone. An analysis of specific complications revealed that postoperative fever (temperature > 100°F) was the most common event, occurring in 27 patients (7.7%). A transient rise in serum creatinine greater than 0.5 mg/dl was observed in 3 cases (0.9%). Bleeding necessitating blood transfusion was required in 11 patients (3.1%). Leakage from the puncture site occurred in 4 patients (1.1%), while pleural injury was noted in 2 patients (0.6%). Pseudoaneurysm requiring angioembolization was observed in 4 patients (1.1%). The median haemoglobin drop was 0.7 g/dl (range: 0–6.4 g/dl). When categorized, 300 patients (85.7%) experienced a haemoglobin drop of less than 1.95 g/dl, while 50 patients (14.3%) had a drop of 1.95 g/dl or greater. According to the Clavien-Dindo classification, most patients (85.1%, n = 298) had no complications. Grade 1 complications were observed in 27 patients (7.7%), Grade 2 complications in 19 patients (5.4%), and Grade 3 complications in 6 patients (1.7%). Major complications, defined as Clavien-Dindo Grade 2 or higher, occurred in 26 patients (7.4%). 3.2. Predictors of stone-free status The stone-free rate at four weeks was 91.7% (321 patients). ROC curve analysis (Table 2 ) revealed that the max CSA had the highest area under the curve (AUC) for predicting SFR (0.722), with a cut-off of ≥ 72° yielding a sensitivity of 69.0% and specificity of 74.5%. The STONE score also showed good predictive ability (AUC 0.710), with a cut-off > 9 providing high specificity (85.0%). Calyx diameter and calyx-pelvis distance had lower predictive values (AUC 0.611 and 0.596, respectively), while IPA had no predictive value (AUC 9 48.3 85.0 Calyx diameter 0.611 < 1.35 cm 62.1 56.4 Calyx-pelvis distance 0.596 < 4 cm 48.3 69.2 Maximum calyx-stone angle 0.722 ≥ 72° 69.0 74.5 Infundibulopelvic angle 9 and a max CSA ≥ 72° were significantly associated with residual stones (p = 0.000 for both). Multivariate logistic regression analysis identified tract length > 10 cm (p = 0.011) and GUY’S Score Grade 1 compared to non-Grade 1 (p = 0.018) as significant independent predictors of stone-free status. The model demonstrated good fit (Hosmer and Lemeshow p = 0.846). Table 3 Association of Anatomical Parameters (at Optimal Cut-offs) with Stone-Free Rate Parameter Subgroup Stone Free (n = 321) Residual Stone (n = 29) P Value STONE score > 9 48 (15.0%) 14 (48.3%) 0.000 <= 9 273 (85.0%) 15 (51.7%) Calyx diameter ≥ 1.35 140 (43.6%) 18 (62.1%) 0.056 < 1.35 181 (56.4%) 11 (37.9%) Calyx-pelvis distance ≥ 4 cm 112 (34.9%) 15 (51.7%) 0.071 < 4cm 209 (65.1%) 14 (48.3%) Maximum Calyx Stone angle ≥ 72° 82 (25.5%) 20 (69.0%) 0.000 < 72° 239 (74.5%) 9 (31.0%) 3.3. Predictors of Major Complications (CD ≥ 2) Major complications occurred in 26 patients (7.4%). Univariate analysis showed that stone density ≤ 950 HU (p = 0.005), staghorn calculi (p = 0.022), intraoperative bleeding (p = 0.000), nephrostomy tube requirement (p = 0.000), and longer operative time (p = 0.009) were associated with major complications. Multivariate analysis confirmed stone density ≤ 950 HU (p = 0.001) and intraoperative bleeding (p = 0.006) as independent predictors, with nephrostomy tube requirement showing a trend (p = 0.069). 3.3 Predictors of Significant Drop in Haemoglobin A significant haemoglobin drop (≥ 1.95 g/dl) occurred in 50 patients (14.3%). On univariate analysis, moderate-to-severe hydronephrosis (p = 0.007), max CSA ≥ 72° (p = 0.005), multiple tracts (p = 0.004), intraoperative bleeding (p = 0.004), and nephrostomy tube requirement (p = 0.000) were significant. Multivariate analysis identified nephrostomy tube requirement (p = 0.032), higher hydronephrosis grade (p = 0.042), max CSA ≥ 72° (p = 0.008), and multiple tracts (p = 0.021) as independent predictors. 4. Discussion This prospective study of 350 patients provides a comprehensive analysis of the role of calyceal anatomy in determining outcomes after PCNL. Our findings confirm that while patient and stone factors remain important, specific anatomical parameters, particularly the maximum calyx-stone angle, are significant independent predictors of stone-free status and perioperative morbidity. The overall SFR of 91.7% in our study is consistent with high-volume centres and reflects the efficacy of PCNL for large and complex stones ( 1 ). Our most significant finding is the predictive value of the maximum calyx-stone angle. With an AUC of 0.722, it outperformed other anatomical parameters and was comparable to the STONE score in predicting SFR. A max CSA ≥ 72° was associated with a nearly three-fold higher likelihood of residual stones. This novel parameter likely quantifies the angular "path" a nephroscope must navigate to reach the most distant stone fragment. Our study introduces max CSA as a more dynamic and stone-specific metric for PCNL planning. Our findings on the limited predictive value of the infundibulopelvic angle (IPA) alone are noteworthy. While IPA has been a focus of previous anatomical studies ( 5 ), our results suggest that when considered in isolation, it is not a strong predictor of SFR in PCNL. This may be because the angle of approach for a rigid nephroscope is not solely determined by the IPA but also by the calyx selected for puncture and the stone's location within that calyx. This is precisely why the max CSA, which integrates the stone's position, proved superior. Our results are comparable to the recent study by Rathod et al., which was used for our sample size calculation ( 6 ). They found infundibular length and infundibulopelvic angle to be significant predictors of SFR, while our study found max CSA and tract length to be more important. This discrepancy could be due to differences in measurement techniques (retrograde pyelogram vs. CT urography) or patient populations. Our use of intraoperative retrograde pyelograms allowed for standardized, real-time measurements during the procedure, potentially offering a more accurate representation of the anatomy as encountered by the surgeon. The study by Patel et al. ( 7 ) also emphasized the importance of calyceal anatomy, reporting that an infundibular width < 10 mm and an IPA < 45° were associated with lower SFR and longer operative times. Regarding complications, our finding that a significant haemoglobin drop was independently predicted by a max CSA ≥ 72°. A larger angle means more angulation at the infundibulum which may cause torque and bleeding. The significant association with multiple tracts and nephrostomy tube requirement further supports this, suggesting that these cases are technically more demanding and thus carry a higher risk of bleeding. The independent prediction of major complications by stone density ≤ 950 HU (softer stones) is interesting. It might be that softer stones fragment into smaller, more numerous pieces that are harder to completely clear, leading to longer operative times and increased manipulation, thereby increasing complication risk ( 8 ). Alternatively, it may be a marker for different stone composition (e.g., infection stones), which are associated with higher infectious complications. The strengths of our study include its prospective design, large sample size, and the use of standardized intraoperative measurements from retrograde pyelograms. This allowed for precise, real-world quantification of the anatomy. However, we acknowledge limitations. The study is from a single centre, which may limit generalizability. The measurements, while standardized, were performed by a single investigator using a software application, introducing potential for measurement bias. Furthermore, the definition of stone-free status using ultrasound at 4 weeks, while clinically relevant, is less sensitive than non-contrast CT. 5. Conclusion Calyceal anatomy plays a critical role in determining the success and safety of PCNL. The maximum calyx-stone angle, a novel and measurable parameter on retrograde pyelogram, is a significant independent predictor of stone-free status. Anatomical factors, along with clinical parameters, also influence the risk of bleeding and other complications. Preoperative assessment of these anatomical metrics, particularly the maximum calyx-stone angle, should be incorporated into surgical planning to optimize access selection, anticipate technical challenges, and improve patient counselling. Declarations Declaration of AI use in scientific writing: Use of Artificial Intelligence: During the preparation of this manuscript, the author(s) used DeepSeek (DeepSeek-V3, DeepSeek Inc.) in March 2026 for language editing and to improve readability. After using this tool, the author(s) reviewed and edited the content as needed and take(s) full responsibility for the content of the publication. Financial Support / Disclosure No financial support was received for this study. Conflicts of Interest The authors declare that they have no conflict of interest. Ethics Approval This study was approved by the Nobel Medical College Institutional Review Board. All procedures performed were in accordance with the ethical standards of the institutional research committee. Author Contribution K.M. wrote the main manuscript text and prepared figure and tables. A.P. and R.S.S. reviewed the manuscript. Data Availability All data supporting the findings of this study are available within the paper. References Türk C, Petřík A, Sarica K, Seitz C, Skolarikos A, Straub M et al (2016) EAU Guidelines on Interventional Treatment for Urolithiasis. Eur Urol 69(3):475–482 Akman T, Binbay M, Yuruk E, Sari E, Seyrek M, Kaba M et al (2011) Factors affecting bleeding during percutaneous nephrolithotomy. Urology 77(4):830–834 Thomas K, Smith NC, Hegarty N, Glass JM (2011) The Guy's stone score–grading the complexity of percutaneous nephrolithotomy procedures. Urology 78(2):277–281 Okhunov Z, Friedlander JI, George AK, Duty BD, Moreira DM, Srinivasan AK et al (2013) S.T.O.N.E. nephrolithometry: novel surgical classification system for kidney calculi. Urology 81(6):1154–1159 Sampaio FJ, Aragão AH (1990) Anatomical relationship between the intrarenal arteries and the kidney collecting system. J Urol 143(4):679–681 Rathod R, Sharma G, Sinha RJ, Singh V (2025) Role of Pelvicalyceal Anatomy in Predicting Outcomes of Percutaneous Nephrolithotomy: A Prospective Study. J Endourol 39(1):22–28 Patel SR, Nakada SY (2016) The role of calyceal anatomy in percutaneous nephrolithotomy. Indian J Urol 32(3):185–190 El-Nahas AR, Shokeir AA, El-Assmy AM, Mohsen T, Shoma AM, Eraky I et al (2007) post-percutaneous nephrolithotomy extensive hemorrhage: a study of risk factors. J Urol 177(2):576–579 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-9187056","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":611375442,"identity":"a83af350-5eda-40fb-81bb-f5ad4e3c9905","order_by":0,"name":"Kartikesh Mishra","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxUlEQVRIiWNgGAWjYBACCQYGZhAtByIOPCBOCzNYizFYSwIpWhIbQCRRWiRnnz9sXFBxJ31+2OGHQFvs5HQbCGiR5ktmTp5x5lnuxttpBkAtycZmBwhokeNhZj7M23Y4d+PsBJCWA4nbiNPy73C64ez0D8RpkQZqSeZtOJwgL51DpC2SPczGxjzHnhlukM4pOJBgQIRfJM4wPpbmqbkjLz87ffOHDxV2cgS1QMEBBgOwSgPilEO0yDcQr3oUjIJRMApGGAAAzh1CPKKKbUEAAAAASUVORK5CYII=","orcid":"","institution":"Nobel Medical College and Teaching Hospital","correspondingAuthor":true,"prefix":"","firstName":"Kartikesh","middleName":"","lastName":"Mishra","suffix":""},{"id":611375443,"identity":"bb382f9f-33f4-4835-ae47-d61f275c7fa9","order_by":1,"name":"Ram Sagar Shah","email":"","orcid":"","institution":"Nobel Medical College and Teaching Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ram","middleName":"Sagar","lastName":"Shah","suffix":""},{"id":611375444,"identity":"92118cc0-1ae6-40bf-9a27-44eb013515fb","order_by":2,"name":"Abhisekh Paudel","email":"","orcid":"","institution":"Nobel Medical College and Teaching Hospital","correspondingAuthor":false,"prefix":"","firstName":"Abhisekh","middleName":"","lastName":"Paudel","suffix":""}],"badges":[],"createdAt":"2026-03-21 16:23:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9187056/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9187056/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105456658,"identity":"c7d950aa-6abb-467d-a75d-9199cd5ff9d5","added_by":"auto","created_at":"2026-03-26 09:15:13","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":538995,"visible":true,"origin":"","legend":"\u003cp\u003eFigure showing method of taking measurements such as Calyx diameter, Calyx pelvis distance, Infundibulopelvic angle and Maximum calyx to stone angle from retrograde pyelogram.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9187056/v1/6c8746149f81d6252aa8bba2.png"},{"id":105791818,"identity":"f0f00502-324d-4657-8edc-0e03c27aabcd","added_by":"auto","created_at":"2026-03-31 07:44:17","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1496695,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9187056/v1/37a83166-733c-4449-afe9-c8e5e7ac8243.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eThe Critical Role of Calyceal Anatomy in Achieving Stone-Free Status After PCNL: A Prospective Study\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003ePercutaneous nephrolithotomy (PCNL) has been the gold-standard treatment for large renal calculi (\u0026gt;\u0026thinsp;2 cm) since its inception in the 1970s, establishing itself as a highly effective procedure with superior stone-free rates (SFRs) compared to shockwave lithotripsy (SWL) or retrograde intrarenal surgery (RIRS) for such stones (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). The fundamental procedure involves gaining percutaneous access into the collecting system, dilating the tract, and using endoscopic instruments to fragment and remove stones.\u003c/p\u003e \u003cp\u003eNumerous patient-specific and stone-specific factors have been extensively studied and identified as predictors of these outcomes. Key among them are stone burden (size and volume), stone density (Hounsfield Units), stone location, patient comorbidities, and Body Mass Index (BMI) (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). The Guy\u0026rsquo;s Stone Score and the S.T.O.N.E. nephrolithometry score are examples of pre-operative grading systems that incorporate many of these factors to predict SFR (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe renal collecting system is not a passive chamber but a complex, three-dimensional structure with significant anatomical variation. Key anatomical elements include the renal calyces, which are the chambers that collect urine; the infundibula, which are the narrow channels connecting the calyces to the renal pelvis; and the various angles formed between these structures.\u003c/p\u003e \u003cp\u003eThe initial step of obtaining optimal percutaneous access is arguably the most crucial, and it is profoundly influenced by the spatial orientation of the calyces and their relationship to the stone. Once access is established, the surgeon must manoeuvre the nephroscope through the infundibula to reach and clear all stone fragments. It is at this stage that anatomical constraints become critically important. A narrow, long, or acutely angled infundibulum can impede the passage of rigid scopes, limit irrigation flow, trap fragments, and complicate the use of lithotripters, potentially leading to incomplete stone clearance or increased risk of mucosal injury and bleeding (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTraditional pre-operative planning, often based on two-dimensional imaging like intravenous urograms (IVU), fails to fully capture the spatial relationships. The intraoperative pyelogram provides an unprecedented opportunity to precisely measure these anatomical parameters. Therefore, a detailed investigation into specific anatomical metrics\u0026mdash;such as calyceal location, diameter, infundibular dimensions, and critical angulations\u0026mdash;is the necessary next step in refining patient selection, pre-operative planning, and prognostic prediction for PCNL.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Study Design and Setting\u003c/h2\u003e \u003cp\u003eThis was a prospective, observational study conducted on consecutive patients undergoing PCNL between July 15, 2025, and December 15, 2025. Institutional ethical committee approval was obtained, and written informed consent was taken from all participants.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Participants\u003c/h2\u003e \u003cp\u003eAll adult patients scheduled for PCNL were assessed for eligibility. The inclusion criteria were: (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) patients with renal stones\u0026thinsp;\u0026gt;\u0026thinsp;2 cm in the pelvicalyceal system, and (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) patients with stones\u0026thinsp;\u0026lt;\u0026thinsp;2 cm for whom PCNL was deemed the most appropriate intervention by the treating surgeon. Patients were excluded if they had: (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) uncorrected coagulopathy or were on anticoagulant therapy; (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) an active urinary tract infection or urosepsis at the time of surgery; (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) a known pregnancy; (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e) incomplete data or were lost to follow-up; or (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e) no preoperative computed tomography (CT) scan available for analysis.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Sample Size Calculation\u003c/h2\u003e \u003cp\u003eThe sample size was calculated based on a similar study by Rathod et al. (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). Using a two-tailed alpha of 0.05 and 90% power, the required sample size was 25 patients per group. Accounting for a high success rate (86.67%) and a smaller failure group, the total sample size was estimated to be 188. To enhance the robustness of our findings, we enrolled 350 patients.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. \u003cb\u003eMeasurements on retrograde pyelogram\u003c/b\u003e:\u003c/h2\u003e \u003cp\u003ePatients were initially placed in the lithotomy position for the cystoscopic placement of a 5\u0026ndash;6 Fr ureteral catheter. Patients were then repositioned prone. Retrograde pyelogram was performed mostly with air (\u0026lt;\u0026thinsp;10ml) with gentle push and meglumine diatriazoate (76%) was used whenever it failed. A needle of 10ml syringe which measured 4.5cm in length was placed lateral to the spine of the patient in the prone position and retrograde contrast instillation was done in 0 degree C-ARM position.\u003c/p\u003e \u003cp\u003eThe retrograde pyelogram image was captured by an android mobile version 15AP3A.240905. 015.A2 with OS version 2.0.210.0. VNQINXM from the C-ARM monitor. ImageMeter version 3.9.10-1 (license: Free Evaluation) was used to perform measurements. In the ImageMeter application, previously placed needle which measured 4.5cm was take taken as reference scale. Calyx diameter was measured as distance between two furthest points on the circumference at the centre of the calyx. Calyx to pelvis distance was measured from the centre of the calyx to the centre of the pelvis. Infundibulopelvic angle (IPA) of the selected calyx was measured as the supplementary angle formed by the ureteric line and the calyx to pelvis line. Maximum Calyx to stone angle (max CSA) was defined as the angle formed by the calyx to pelvis line and the line joining the pelvis and lateral most calculus. This angle came out to be the sum of Infundibulopelvic angle and angle formed by the ureteric line and the line joining pelvis and lateral most calculus. As in the Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, lateral most stone is present at point B in the lower calyx, thus maximum calyx to stone angle was angle COB\u0026thinsp;=\u0026thinsp;angle COU +angle UOB. Angle COU\u0026thinsp;=\u0026thinsp;angle AOU\u0026rsquo; (vertically opposite angles) = Infundibulopelvic angle (IPA). Hence, maximum calyx to stone angle COB\u0026thinsp;=\u0026thinsp;IPA\u0026thinsp;+\u0026thinsp;angle UOB (angle formed by ureteric line and lateralmost calculus). In the Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, IPA\u0026thinsp;=\u0026thinsp;180\u0026thinsp;\u0026minus;\u0026thinsp;120=60, angle UOB\u0026thinsp;=\u0026thinsp;75, thus max CSA\u0026thinsp;=\u0026thinsp;60\u0026thinsp;+\u0026thinsp;75\u0026thinsp;=\u0026thinsp;135.\u003c/p\u003e \u003cp\u003eDiameter of the infundibulum was judged preoperatively whether 18Fr amplatz sheath could be negotiated through the infundibulum or not. As presence of bleeding intraoperatively could affect stone free rate and predict major complication, it was noted and later analysed. Similarly, note regarding need of nephrostomy tube was made and its relationship with major complication was later analysed.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Data Collection and Outcome Measures\u003c/h2\u003e \u003cp\u003ePreoperative data included patient demographics, comorbidities, and stone characteristics (size, density, Guy's and STONE scores). Intraoperative data included calyceal measurements, number of access attempts, fluoroscopy time, and operative time. Postoperative outcomes assessed were:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eStone-Free Rate (SFR)\u003c/b\u003e: Defined as the absence of any residual stone fragments\u0026thinsp;\u0026gt;\u0026thinsp;4 mm on ultrasound imaging at 4 weeks post-procedure.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eSafety\u003c/b\u003e: All complications were recorded and graded according to the Clavien-Dindo (CD) classification system. Major complications were defined as CD Grade\u0026thinsp;\u0026ge;\u0026thinsp;2.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eOther parameters\u003c/b\u003e: Included drop in haemoglobin, need for blood transfusion, hospital stay, and requirement for secondary interventions.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Statistical Analysis\u003c/h2\u003e \u003cp\u003eData were analysed using IBM SPSS version 26. Continuous variables were presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation or median (range), and categorical variables as frequencies and percentages. ROC curve analysis was used to determine predictive cut-offs. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of outcomes.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Patient Demographics and Baseline Characteristics\u003c/h2\u003e \u003cp\u003eA total of 350 patients were included. The baseline demographics and clinical characteristics are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The median age was 40 years, with a slight male predominance (52.3%). The median STONE score was 7, and most patients had moderate (63.1%) or high (27.1%) complexity stones. The most frequently selected calyx for puncture was the upper compound calyx (56.0%). The median calyx diameter was 1.3 cm, median calyx-to-pelvis length was 3.5 cm, median IPA was 37 degrees, and median max CSA was 0 degrees.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBaseline demographics and clinical characteristics\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSubgroup / Finding\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFrequency (n)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePercentage (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMedian (Range)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e40 (2\u0026ndash;87)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale: Female\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e183: 167\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRatio: 1.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComorbidities\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHypertension (HTN)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDiabetes Mellitus (DM)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOther Comorbidity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSurgical History\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHistory of ipsilateral PCNL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHistory of ipsilateral open renal surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePreoperative Labs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePreoperative Hb (gm/dl) *\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12.8 (8-18.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePreoperative Cr (mg/dl)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.9 (0.5\u0026ndash;3.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStone Characteristics\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStone Size (mm\u0026sup2;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;400 mm\u0026sup2;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e21.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e400\u0026ndash;799 mm\u0026sup2;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e800\u0026ndash;1599 mm\u0026sup2;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e117\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e33.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;1600 mm\u0026sup2;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTract Length (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;10 cm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e332\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e94.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;10 cm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHydronephrosis Grade\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNone or mild\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e275\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e78.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eModerate to severe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e21.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of Calices Involved\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u0026ndash;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e266\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e76.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStaghorn\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16.9%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStone Density (HU)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;950 HU\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e163\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e46.6%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;950 HU\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e187\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e53.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComplexity Scores\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSTONE Score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal Score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7 (5\u0026ndash;13)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComplexity Groups\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLow\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9.7%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eModerate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e221\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e63.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHigh\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e27.1%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGUY'S Score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGrade 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e190\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e54.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGrade 2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e26.0%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGrade 3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGrade 4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16.3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*Mean value\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eRegarding the chosen calyx for puncture, the upper compound calyx was the most frequently selected, accounting for 56.0% (n\u0026thinsp;=\u0026thinsp;196) of cases, followed by the middle posterior calyx in 32.0% (n\u0026thinsp;=\u0026thinsp;112). The remaining punctures were distributed among the middle anterior (1.1%, n\u0026thinsp;=\u0026thinsp;4), lower posterior (6.9%, n\u0026thinsp;=\u0026thinsp;24), and lower compound calyces (4.0%, n\u0026thinsp;=\u0026thinsp;14). The median calyx diameter was 1.3 cm (range: 0.4\u0026ndash;6 cm), while the median calyx-to-pelvis length was 3.5 cm (range: 0.8\u0026ndash;7.9 cm). The median infundibulopelvic angle was 37 degrees (range: 0\u0026ndash;140 degrees), and the median maximum calyx-stone angle was 0 degrees (range: 0\u0026ndash;180 degrees). The infundibular diameter of the selected calyx was greater than 18 Fr in most patients (94.9%, n\u0026thinsp;=\u0026thinsp;332).\u003c/p\u003e \u003cp\u003eThe stone-free rate at four weeks was 91.7%, with 321 patients (91.7%) demonstrating no residual stone.\u003c/p\u003e \u003cp\u003eAn analysis of specific complications revealed that postoperative fever (temperature\u0026thinsp;\u0026gt;\u0026thinsp;100\u0026deg;F) was the most common event, occurring in 27 patients (7.7%). A transient rise in serum creatinine greater than 0.5 mg/dl was observed in 3 cases (0.9%). Bleeding necessitating blood transfusion was required in 11 patients (3.1%). Leakage from the puncture site occurred in 4 patients (1.1%), while pleural injury was noted in 2 patients (0.6%). Pseudoaneurysm requiring angioembolization was observed in 4 patients (1.1%).\u003c/p\u003e \u003cp\u003eThe median haemoglobin drop was 0.7 g/dl (range: 0\u0026ndash;6.4 g/dl). When categorized, 300 patients (85.7%) experienced a haemoglobin drop of less than 1.95 g/dl, while 50 patients (14.3%) had a drop of 1.95 g/dl or greater. According to the Clavien-Dindo classification, most patients (85.1%, n\u0026thinsp;=\u0026thinsp;298) had no complications. Grade 1 complications were observed in 27 patients (7.7%), Grade 2 complications in 19 patients (5.4%), and Grade 3 complications in 6 patients (1.7%). Major complications, defined as Clavien-Dindo Grade 2 or higher, occurred in 26 patients (7.4%).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Predictors of stone-free status\u003c/h2\u003e \u003cp\u003eThe stone-free rate at four weeks was 91.7% (321 patients). ROC curve analysis (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) revealed that the max CSA had the highest area under the curve (AUC) for predicting SFR (0.722), with a cut-off of \u0026ge;\u0026thinsp;72\u0026deg; yielding a sensitivity of 69.0% and specificity of 74.5%. The STONE score also showed good predictive ability (AUC 0.710), with a cut-off \u0026gt;\u0026thinsp;9 providing high specificity (85.0%). Calyx diameter and calyx-pelvis distance had lower predictive values (AUC 0.611 and 0.596, respectively), while IPA had no predictive value (AUC\u0026thinsp;\u0026lt;\u0026thinsp;0.5).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eROC Curve Analysis for Prediction of Stone-Free Rate\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAUC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCut-off Value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSensitivity (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSpecificity (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSTONE score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.710\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e48.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e85.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalyx diameter\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.611\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1.35 cm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e62.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e56.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalyx-pelvis distance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.596\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;4 cm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e48.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e69.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMaximum calyx-stone angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.722\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;72\u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e69.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e74.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInfundibulopelvic angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eOn univariate analysis (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), a STONE score\u0026thinsp;\u0026gt;\u0026thinsp;9 and a max CSA\u0026thinsp;\u0026ge;\u0026thinsp;72\u0026deg; were significantly associated with residual stones (p\u0026thinsp;=\u0026thinsp;0.000 for both). Multivariate logistic regression analysis identified tract length\u0026thinsp;\u0026gt;\u0026thinsp;10 cm (p\u0026thinsp;=\u0026thinsp;0.011) and GUY\u0026rsquo;S Score Grade 1 compared to non-Grade 1 (p\u0026thinsp;=\u0026thinsp;0.018) as significant independent predictors of stone-free status. The model demonstrated good fit (Hosmer and Lemeshow p\u0026thinsp;=\u0026thinsp;0.846).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAssociation of Anatomical Parameters (at Optimal Cut-offs) with Stone-Free Rate\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSubgroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStone Free (n\u0026thinsp;=\u0026thinsp;321)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eResidual Stone (n\u0026thinsp;=\u0026thinsp;29)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP Value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSTONE score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e48 (15.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e14 (48.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;= 9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e273 (85.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e15 (51.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalyx diameter\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;1.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e140 (43.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e18 (62.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.056\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e181 (56.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e11 (37.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalyx-pelvis distance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;4 cm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e112 (34.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e15 (51.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.071\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;4cm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e209 (65.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e14 (48.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMaximum Calyx Stone angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;72\u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e82 (25.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e20 (69.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;72\u0026deg;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e239 (74.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e9 (31.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.3. \u003cb\u003ePredictors of Major Complications (CD\u0026thinsp;\u0026ge;\u0026thinsp;2)\u003c/b\u003e\u003c/h2\u003e \u003cp\u003eMajor complications occurred in 26 patients (7.4%). Univariate analysis showed that stone density\u0026thinsp;\u0026le;\u0026thinsp;950 HU (p\u0026thinsp;=\u0026thinsp;0.005), staghorn calculi (p\u0026thinsp;=\u0026thinsp;0.022), intraoperative bleeding (p\u0026thinsp;=\u0026thinsp;0.000), nephrostomy tube requirement (p\u0026thinsp;=\u0026thinsp;0.000), and longer operative time (p\u0026thinsp;=\u0026thinsp;0.009) were associated with major complications. Multivariate analysis confirmed stone density\u0026thinsp;\u0026le;\u0026thinsp;950 HU (p\u0026thinsp;=\u0026thinsp;0.001) and intraoperative bleeding (p\u0026thinsp;=\u0026thinsp;0.006) as independent predictors, with nephrostomy tube requirement showing a trend (p\u0026thinsp;=\u0026thinsp;0.069).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Predictors of Significant Drop in Haemoglobin\u003c/h2\u003e \u003cp\u003eA significant haemoglobin drop (\u0026ge;\u0026thinsp;1.95 g/dl) occurred in 50 patients (14.3%). On univariate analysis, moderate-to-severe hydronephrosis (p\u0026thinsp;=\u0026thinsp;0.007), max CSA\u0026thinsp;\u0026ge;\u0026thinsp;72\u0026deg; (p\u0026thinsp;=\u0026thinsp;0.005), multiple tracts (p\u0026thinsp;=\u0026thinsp;0.004), intraoperative bleeding (p\u0026thinsp;=\u0026thinsp;0.004), and nephrostomy tube requirement (p\u0026thinsp;=\u0026thinsp;0.000) were significant. Multivariate analysis identified nephrostomy tube requirement (p\u0026thinsp;=\u0026thinsp;0.032), higher hydronephrosis grade (p\u0026thinsp;=\u0026thinsp;0.042), max CSA\u0026thinsp;\u0026ge;\u0026thinsp;72\u0026deg; (p\u0026thinsp;=\u0026thinsp;0.008), and multiple tracts (p\u0026thinsp;=\u0026thinsp;0.021) as independent predictors.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThis prospective study of 350 patients provides a comprehensive analysis of the role of calyceal anatomy in determining outcomes after PCNL. Our findings confirm that while patient and stone factors remain important, specific anatomical parameters, particularly the maximum calyx-stone angle, are significant independent predictors of stone-free status and perioperative morbidity.\u003c/p\u003e \u003cp\u003eThe overall SFR of 91.7% in our study is consistent with high-volume centres and reflects the efficacy of PCNL for large and complex stones (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). Our most significant finding is the predictive value of the maximum calyx-stone angle. With an AUC of 0.722, it outperformed other anatomical parameters and was comparable to the STONE score in predicting SFR. A max CSA\u0026thinsp;\u0026ge;\u0026thinsp;72\u0026deg; was associated with a nearly three-fold higher likelihood of residual stones. This novel parameter likely quantifies the angular \"path\" a nephroscope must navigate to reach the most distant stone fragment. Our study introduces max CSA as a more dynamic and stone-specific metric for PCNL planning.\u003c/p\u003e \u003cp\u003eOur findings on the limited predictive value of the infundibulopelvic angle (IPA) alone are noteworthy. While IPA has been a focus of previous anatomical studies (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e), our results suggest that when considered in isolation, it is not a strong predictor of SFR in PCNL. This may be because the angle of approach for a rigid nephroscope is not solely determined by the IPA but also by the calyx selected for puncture and the stone's location within that calyx. This is precisely why the max CSA, which integrates the stone's position, proved superior.\u003c/p\u003e \u003cp\u003eOur results are comparable to the recent study by Rathod et al., which was used for our sample size calculation (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). They found infundibular length and infundibulopelvic angle to be significant predictors of SFR, while our study found max CSA and tract length to be more important. This discrepancy could be due to differences in measurement techniques (retrograde pyelogram vs. CT urography) or patient populations. Our use of intraoperative retrograde pyelograms allowed for standardized, real-time measurements during the procedure, potentially offering a more accurate representation of the anatomy as encountered by the surgeon. The study by Patel et al. (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e) also emphasized the importance of calyceal anatomy, reporting that an infundibular width\u0026thinsp;\u0026lt;\u0026thinsp;10 mm and an IPA\u0026thinsp;\u0026lt;\u0026thinsp;45\u0026deg; were associated with lower SFR and longer operative times.\u003c/p\u003e \u003cp\u003eRegarding complications, our finding that a significant haemoglobin drop was independently predicted by a max CSA\u0026thinsp;\u0026ge;\u0026thinsp;72\u0026deg;. A larger angle means more angulation at the infundibulum which may cause torque and bleeding. The significant association with multiple tracts and nephrostomy tube requirement further supports this, suggesting that these cases are technically more demanding and thus carry a higher risk of bleeding. The independent prediction of major complications by stone density\u0026thinsp;\u0026le;\u0026thinsp;950 HU (softer stones) is interesting. It might be that softer stones fragment into smaller, more numerous pieces that are harder to completely clear, leading to longer operative times and increased manipulation, thereby increasing complication risk (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e). Alternatively, it may be a marker for different stone composition (e.g., infection stones), which are associated with higher infectious complications.\u003c/p\u003e \u003cp\u003eThe strengths of our study include its prospective design, large sample size, and the use of standardized intraoperative measurements from retrograde pyelograms. This allowed for precise, real-world quantification of the anatomy. However, we acknowledge limitations. The study is from a single centre, which may limit generalizability. The measurements, while standardized, were performed by a single investigator using a software application, introducing potential for measurement bias. Furthermore, the definition of stone-free status using ultrasound at 4 weeks, while clinically relevant, is less sensitive than non-contrast CT.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eCalyceal anatomy plays a critical role in determining the success and safety of PCNL. The maximum calyx-stone angle, a novel and measurable parameter on retrograde pyelogram, is a significant independent predictor of stone-free status. Anatomical factors, along with clinical parameters, also influence the risk of bleeding and other complications. Preoperative assessment of these anatomical metrics, particularly the maximum calyx-stone angle, should be incorporated into surgical planning to optimize access selection, anticipate technical challenges, and improve patient counselling.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eDeclaration of AI use in scientific writing:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eUse of Artificial Intelligence: During the preparation of this manuscript, the author(s) used DeepSeek (DeepSeek-V3, DeepSeek Inc.) in March 2026 for language editing and to improve readability. After using this tool, the author(s) reviewed and edited the content as needed and take(s) full responsibility for the content of the publication.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eFinancial Support / Disclosure\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo financial support was received for this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Nobel Medical College Institutional Review Board. All procedures performed were in accordance with the ethical standards of the institutional research committee.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eK.M. wrote the main manuscript text and prepared figure and tables. A.P. and R.S.S. reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eAll data supporting the findings of this study are available within the paper.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eT\u0026uuml;rk C, Petř\u0026iacute;k A, Sarica K, Seitz C, Skolarikos A, Straub M et al (2016) EAU Guidelines on Interventional Treatment for Urolithiasis. Eur Urol 69(3):475\u0026ndash;482\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAkman T, Binbay M, Yuruk E, Sari E, Seyrek M, Kaba M et al (2011) Factors affecting bleeding during percutaneous nephrolithotomy. Urology 77(4):830\u0026ndash;834\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThomas K, Smith NC, Hegarty N, Glass JM (2011) The Guy's stone score\u0026ndash;grading the complexity of percutaneous nephrolithotomy procedures. Urology 78(2):277\u0026ndash;281\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOkhunov Z, Friedlander JI, George AK, Duty BD, Moreira DM, Srinivasan AK et al (2013) S.T.O.N.E. nephrolithometry: novel surgical classification system for kidney calculi. Urology 81(6):1154\u0026ndash;1159\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSampaio FJ, Arag\u0026atilde;o AH (1990) Anatomical relationship between the intrarenal arteries and the kidney collecting system. J Urol 143(4):679\u0026ndash;681\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRathod R, Sharma G, Sinha RJ, Singh V (2025) Role of Pelvicalyceal Anatomy in Predicting Outcomes of Percutaneous Nephrolithotomy: A Prospective Study. J Endourol 39(1):22\u0026ndash;28\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePatel SR, Nakada SY (2016) The role of calyceal anatomy in percutaneous nephrolithotomy. Indian J Urol 32(3):185\u0026ndash;190\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEl-Nahas AR, Shokeir AA, El-Assmy AM, Mohsen T, Shoma AM, Eraky I et al (2007) post-percutaneous nephrolithotomy extensive hemorrhage: a study of risk factors. J Urol 177(2):576\u0026ndash;579\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"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":"Nephrolithotomy, Kidney Calices, Treatment Outcome, Postoperative Complications, Predictive Value of Tests, Retrograde Pyelography","lastPublishedDoi":"10.21203/rs.3.rs-9187056/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9187056/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIntroduction: Percutaneous nephrolithotomy (PCNL) is the gold standard for large renal calculi.This study aimed to prospectively evaluate the impact of specific anatomical parameters, measured on retrograde pyelogram, on stone-free rates (SFR) and perioperative outcomes after PCNL.\u003c/p\u003e \u003cp\u003eMethods: This prospective, observational study included 350 patients who underwent PCNL. Preoperative anatomical parameters\u0026mdash;including calyx diameter, calyx-to-pelvis distance, infundibulopelvic angle (IPA), and maximum calyx-stone angle (max CSA) were measured on retrograde pyelograms. Outcomes assessed were SFR at 4 weeks, complications (Clavien-Dindo), and haemoglobin drop. Statistical analysis included ROC curve, univariate, and multivariate regression analyses.\u003c/p\u003e \u003cp\u003eResults: The overall SFR was 91.7%. ROC analysis identified max CSA as the strongest anatomical predictor of SFR (AUC 0.722), with a cut-off of \u0026ge;\u0026thinsp;72\u0026deg; (sensitivity 69.0%, specificity 74.5%). On multivariate analysis, tract length\u0026thinsp;\u0026gt;\u0026thinsp;10 cm (p\u0026thinsp;=\u0026thinsp;0.011) and GUY\u0026rsquo;S Score Grade 1 (p\u0026thinsp;=\u0026thinsp;0.018) were independent predictors of SFR. Major complications (Clavien-Dindo\u0026thinsp;\u0026ge;\u0026thinsp;2) occurred in 7.4% and were independently predicted by stone density\u0026thinsp;\u0026le;\u0026thinsp;950 HU (p\u0026thinsp;=\u0026thinsp;0.001) and intraoperative bleeding (p\u0026thinsp;=\u0026thinsp;0.006). A significant haemoglobin drop (\u0026ge;\u0026thinsp;1.95 g/dl) was independently associated with nephrostomy tube requirement (p\u0026thinsp;=\u0026thinsp;0.032), higher hydronephrosis grade (p\u0026thinsp;=\u0026thinsp;0.042), max CSA\u0026thinsp;\u0026ge;\u0026thinsp;72\u0026deg; (p\u0026thinsp;=\u0026thinsp;0.008), and multiple tracts (p\u0026thinsp;=\u0026thinsp;0.021).\u003c/p\u003e \u003cp\u003eConclusion: Calyceal anatomy, particularly the maximum calyx-stone angle, is a significant predictor of stone-free status after PCNL. Anatomical parameters also play a role in perioperative morbidity. Preoperative assessment of these factors can aid in surgical planning and patient counselling.\u003c/p\u003e","manuscriptTitle":"The Critical Role of Calyceal Anatomy in Achieving Stone-Free Status After PCNL: A Prospective Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-26 09:15:08","doi":"10.21203/rs.3.rs-9187056/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":"7ced6c58-2015-4ce5-baed-0482d02fc430","owner":[],"postedDate":"March 26th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-03-31T07:43:56+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-26 09:15:08","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9187056","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9187056","identity":"rs-9187056","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}