Active migration technique versus in situ lithotripsy technique in RIRS for 1-2 cm middle and upper ureteral stones: a prospective, randomized controlled study

Active migration technique versus in situ lithotripsy technique in RIRS for 1-2 cm middle and upper ureteral stones: a prospective, randomized controlled 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 Active migration technique versus in situ lithotripsy technique in RIRS for 1-2 cm middle and upper ureteral stones: a prospective, randomized controlled study Ping Liang, Qing-lai Tang, Jia-yan Ji, Yu-xin Zhang, Yun-peng Li, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8924143/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 To observe the efficacy and safety of the active migration technique and in situ lithotripsy technique in retrograde intrarenal surgery (RIRS) for patients with 1–2 cm middle and upper ureteral stones. 207 patients were enrolled in the study, of which 103 included in the study group received active migration lithotripsy and 104 included in the control group received in situ lithotripsy. The primary study outcome was the stone-free rate (SFR) on the first postoperative day. Secondary outcomes included the total SFR 4 weeks postoperatively, operative time, reduction in the hemoglobin levels, the length of postoperative hospital stay, the incidence of ureteral stricture at 3-month postoperatively, and any surgery-related complications. There was no obvious difference between two groups in patients’ demographics and preoperative clinical characteristics ( P > 0.05). The operative time was significantly shorter in the study group than in the control group (57.1 vs. 62.5 min, P < 0.001). The study group also had significantly higher immediate and total SFRs (81.5% vs. 64.4%, P = 0.006, 90.3% vs. 77.9%, P = 0.015, respectively). At 3 months postoperatively, the incidence of ureteral stricture in the study was statistically lower than in the control group (1.0% vs. 6.7%, P = 0.032). Notablely, the overall complication rate was significantly lower in the study group than in the control group ( P < 0.001). Our study provides evidence that the active migration technique, when combined with flexible and negative suction ureteral access sheath (FANS) in RIRS, results in a higher SFR and a lower complication rate than in situ lithotripsy for treating 1–2 cm middle and upper ureteral stones. The protocol for this study has been accepted by the Chinese Clinical Trial Registry (The registration number: ChiCTR2200056402; Date of registration: 03-06-2022). Retrograde intrarenal surgery Flexible and negative suction ureteral access sheath Ureteral stones Stone-free rates Active migration technique Figures Figure 1 Figure 2 Figure 3 1 Introduction Ureteral stones are a common condition in urology. Compared with lower ureteral stones, the treatment of middle and upper ureteral stones is often more challenging [ 1 ] . Among the various treatment options for ureteral stones measuring 1–2 cm, retrograde intrarenal surgery (RIRS) has become a widely adopted approach due to its minimally invasive nature compared with percutaneous nephrolithotomy (PCNL) and its greater versatility compared with extracorporeal shock wave lithotripsy (ESWL) [ 2 ] . In line with this, the European Association of Urology (EAU) recommends RIRS as the primary treatment option for ureteral stones ≥ 1 cm [ 3 ] . Most clinicians are accustomed to using ureteroscopy for in situ lithotripsy. However, due to the narrow lumen and natural curvature of the ureter, the laser fiber often cannot make direct contact with the stone, requiring repeated adjustments in angle to achieve lithotripsy [ 4 ] . This not only increases the complexity and duration of the procedure but also easily elevates the risk of ureteral injury. Reported stone-free rates (SFRs) for 1–2 cm middle and upper ureteral stones treated with ureteroscopy vary widely (45.6%-96.7%), largely depending on the surgical strategy employed [ 5 ] . The recent introduction of the flexible and negative suction ureteral access sheath (FANS) in RIRS represents a significant advancement. Studies have shown that combining FANS with RIRS can significantly improve SFR and reduce postoperative complications in patients with upper urinary tract stones [ 6 ] . In our department, we have optimized the treatment strategy for middle and upper ureteral stones by initially pushing the stones into favorable renal calyces—typically the upper and middle calyces—before performing laser lithotripsy. We refer to this approach as the active migration technique. We hypothesize that its advantages include: (1) reducing the need for lithotripsy within the ureter, thereby minimizing ureteral damage; (2) fragmenting stones in a semi-enclosed space, which prevents stone fragments from dispersing throughout the renal pelvis and potentially improves the SFR. To date, no studies have evaluated the use of the active migration technique in combination with FANS for treating middle and upper ureteral stones. Therefore, we conducted a prospective, randomized controlled trial to assess and compare the efficacy and safety of the active migration technique versus the conventional in situ lithotripsy technique in RIRS for patients with 1–2 cm middle and upper ureteral stones. 2 Materials and Methods 2.1 Study Design and Patients Patients with 1-2-cm middle and upper ureteral stones who were referred to our institute were considered for this prospective, randomized controlled study conducted between December 2022 and February 2025. After applying strict inclusion and exclusion criteria, as outlined in Table 1 , the patients were randomly assigned to two groups by using the envelope method. Finally, 207 patients were enrolled in the study, of which 103 included in the study group received active migration lithotripsy and 104 included in the control group received in situ lithotripsy, which was decided based on power analysis performed to estimate the sample size (Fig. 1 ). The participants’ pretreatment evaluation included medical history, physical examination, laboratory investigations (i.e., urine analysis, urine culture and/or sensitivity, complete blood count, blood urea nitrogen, and the serum levels of creatinine, C-reactive protein, and procalcitonin), as well as radiological investigations. Patients with a known urinary tract infection (UTI) received antibiotic treatment until the infection was under control. The study was approved by the clinical research ethics committee of the Affiliated Jiangning Hospital of Nanjing Medical University (ethics approval number: 2025-03-132-K01). Written informed consent was obtained from all participants. The study followed the principles of the Helsinki Declaration. Table 1 The inclusion criteria and exclusion criteria in the study The inclusion criteria: The exclusive criteria: Patients’ age was 18 to 70 years; Uncontrollable UTI and requires drainage; Diagnosed as 1.0–2.0 cm single middle or upper ureteral stones confirmed by CT; Severe cardiovascular and cerebrovascular diseases; No contraindications for surgery; Pregnancy or coagulation disorders; The time from diagnosis to surgery was less than one month. Combining ipsilateral renal stones or bilateral ureteral stones required a one-stage surgery. Ability to provide written informed consent and comply with the trial requirements; History of ureteral stenosis; American Society of Anesthesiology score 1–3. Unable to understand or comply with trial records. 2.2 Randomization and masking Parallel randomization was conducted by using a stratified approach in our study. Our center enrolled 207 participants, who were then randomized in a 1:1 ratio to either the study or the control group. The randomization sequence was arranged electronically before patient inclusion. Consecutively numbered and sealed envelopes were used for random sequence allocation and concealment. After subjecting the patients to general anesthesia and before ureteroscopy was entered into the urethra, the sealed envelope was opened by a designated nurse to reveal the specific surgical approach to be undertaken. Subsequently, after the procedure, the same nurse automatically recorded the operative data. 2.3 Perioperative and surgical procedures All patients underwent preoperative imaging, including plain abdominal radiography of the kidneys, ureters, and bladder (KUB) and non-contrast CT to evaluate hydronephrosis, as well as to assess the size, location, number, and specific details related to the ureteral stones. Accordingly, preprocedural urine cultures were prepared and used in appropriate antibiotic therapy as per the results of the culture-antibiogram test. Patients showing negative urine cultures were treated with broad-spectrum antibiotics before the surgery (i.e., intravenous cefuroxime 1.5 g or levofloxacin 500 mg, if allergic). Otherwise, the procedures were scheduled once the infection indicators displayed a downward trend after the application of sensitive antibiotics (mainly intravenous piperacillin sodium and tazobactam sodium) and after confirming a negative urine culture. The stone size was defined as the largest diameter of a single stone on preoperative KUB and/or non-contrast CT. All procedures were conducted by two urologists, each with experience in conducting more than 200 RIRS procedures annually. The surgical method for the enrolled patients was randomly selected, thereby excluding any subjective bias. 2.3.1 Study group procedure. Under general anesthesia, patients were placed in the Trendelenburg lithotomy position (head down by 30 degrees) for retrograde endoscopic access. A ureteroscopy (STORZ, 8/9.8-Fr) was performed to identify the location of stone obstruction, and the stone was pushed back into the renal pelvis under water flow, the tip of the ureteroscope or guidewire (Bard, USA). Then, a loach guidewire was introduced to access the upper urinary tract, followed by the placement of a 12/14-Fr or 11/13-Fr FANS (length: 40 cm for females; 50 cm for males) (Wellead Medical, Guangdong, China) into the upper affected ureter (Fig. 2 ). The advantage offered by this sheath was that the 3-mm soft tip was designed without a metal spring coil, which provided optimal protection for the ureter mucosa [ 7 ] . Occurrence of ureteral stenosis or distortion during surgery could lead to the failure of FANS implantation; therefore, balloon dilation was attempted as the first line of approach. In cases not feasible for dilation, only a double-J stent was inserted for ureteral expansion. A 7.5-Fr disposable electronic flexible ureteroscope (fURS) (Pusen Medical, Guangdong, China) was then inserted through the FANS and the FANS was adjusted to encase the stone within the renal collecting system (Fig. 3 ). We usually set the fluid irrigation flow to 80–100 mL/min and a negative pressure suction to 85–90 mmHg to obtain a clear surgical view. The lithotripsy process was performed using a holmium laser with a 200-µm laser fiber under an energy of (0.6–0.8 J) * (20–30 Hz). Small fragments were automatically aspirated through the gap between the fURS and FANS, whereas larger fragments required the fURS to be repeatedly inserted and withdrawn slowly under continuous suction from the body ( Supplementary Video 1 ). At the end of the procedure, the fURS was directed toward the collecting system to retrieve any remaining large stone fragments. The FANS and fURS were removed under direct visualization to document and evaluate any ureteral injury [ 8 ] . A 6-Fr double-J stent (Bard, USA) was placed in all patients postoperatively. 2.3.2 Control group procedure. General anesthesia was administered, and the lithotomy position was used for each patient in this group. A ureteroscopy was performed to retrogradely access the ureter until reaching the stone, and the surroundings of the stone were observed. We usually place a stone occlusion device (IVX-SC10; Innovex Medical, Shanghai) along the gap between the stone and the ureteral mucosa above the stone. Presently, the stone was fragmented with a holmium laser using a 200-µm laser fiber (with energy setting < 15 W). Then, the stone fragments were removed using a nitinol stone basket (Cook Medical, USA). Similarly, ureteroscopy was performed to examine the entire ureter, and a 6-Fr double-J stent was indwelt. 2.4 Postoperative follow-up The level of white blood cell counts, C-reactive protein, and procalcitonin at 2-h postoperatively was monitored to screen out serious UTI. Then, 1-mm-thick sections from all patients were subjected to ultra-low-dose, non-contrast CT scanning on the first postoperative day and then at 4 weeks after the surgery to evaluate the immediate and total SFR. Two groups of patients were discharged within 48 h of the surgery if they did not experience any significant discomfort. Every patient received health education before discharge, including recommendations related to precautions, follow-up dates, and emergency contact information. Double-J stents were removed within 4 weeks of the surgery. Meanwhile, the stone composition analyses were performed for all patients to obtain a reference for metabolic analysis and subsequent prevention. Stone-free status was defined as the complete absence of residual stone fragments or the presence of clinically insignificant fragments measuring ≤ 2 mm, asymptomatic, non-obstructive, and non-infectious [ 9 ] . The primary study outcome was the SFR on the first postoperative day. The secondary outcomes included the total SFR 4 weeks postoperatively (evaluated through ultra-low-dose CT), operative time, reduction in the hemoglobin levels, the length of postoperative hospital stay, the incidence of ureteral stricture at 3-month postoperatively, and any surgery-related complications. The operative time was calculated from the time since the ureteroscope was inserted into the urethra up to the time when the double-J tube was placed. Reduction in the hemoglobin levels was deemed indicative of the difference between preoperative hemoglobin levels and the 2-h postoperative hemoglobin level. The length of postoperative hospital stay was counted from the day of surgery to the time of discharge. Importantly, postoperative hydronephrosis was monitored, particularly for ureteral stone patients. Regular urinary ultrasound examinations were conducted for all patients on a monthly basis. Patients were asked to undertake IVU or enhanced CT and provided a follow-up treatment plan if their hydronephrosis had significantly worsened relative to their preoperative imaging at 3 months postoperatively. Postoperative complications were classified using the modified Clavien grading system, including fever (≥ 38.5℃), lower back pain, perirenal hematoma, blood transfusion, and urosepsis [ 10 ] . For patients with residual stones, additional auxiliary procedures were performed at least 4 weeks after the surgery, including external physical vibration lithotripsy, ESWL, or positional therapy, as deemed appropriate [ 11 , 12 ] . 2.5 Statistical analysis Statistical analysis was conducted using IBM SPSS Statistics for Windows, Version 22.0 (IBM Corp., Armonk, NY, USA). Continuous variables were reported as the means ± standard deviations. The independent samples t -test was performed to compare the patient demographics, follow-up data, and surgical outcomes between the groups, whereas the Shapiro–Wilk test was performed to assess the normality of the initial data. For categorical variables, including other pre- and postoperative clinical characteristics, comparisons were made using the Chi-squared test. P < 0.05 was considered to indicate statistical significance. 3 Results 3.1 Demographics and preoperative clinical characteristics In total, 207 patients were randomly assigned to either the study group (n = 103) or the control group (n = 104). No significant differences in baseline demographics or preoperative clinical characteristics were noted between the two groups ( Table 2 ) . The mean stone size was 1.5 cm in the study group and 1.6 cm in the control group. Both groups were also comparable in terms of age, body mass index, sex ratio, history of hypertension or diabetes, ASA classification, stone laterality, stone composition, hydronephrosis grade, urine culture results, and history of previous upper urinary stone surgeries (all P > 0.05). 3.2 Postoperative clinical characteristics Postoperative clinical outcomes are summarized in Table 3 . The mean decrease in hemoglobin and length of postoperative hospital stay did not significantly differ between the two groups (both P > 0.05). However, the operative time was significantly shorter in the study group than in the control group (57.1 vs. 62.5 min, P < 0.001). The study group also had significantly higher immediate and total SFRs (81.5% vs. 64.4%, P = 0.006, 90.3% vs. 77.9%, P = 0.015, respectively). At 3 months postoperatively, ureteral stricture was observed in seven patients in the control group compared with one patient in the study group—a statistically significant difference (6.7% vs. 1.0%, P = 0.032). Regarding postoperative safety, the overall complication rate was significantly lower in the study group than in the control group ( P 38.5°C (2.9% vs. 10.6%, P = 0.028), lower back pain (3.9% vs. 13.5%, P = 0.014), perirenal hematoma (1.3% vs. 7.7%, P = 0.018), and urosepsis (0% vs. 4.8%, P = 0.024) were significantly more frequent in the control group. Blood transfusions were required in two patients in the control group, but in none in the study group, although this difference between the two groups was not statistically significant ( P > 0.05). Postoperative stone composition analysis revealed no significant differences between the two groups ( P > 0.05). Table 2 Comparisons of patients’ demographics and preoperative clinical characteristics between two groups Variables, mean ± SD or n (%) Study group (n = 103) Control group (n = 104) t/ χ 2 value P value Age, years 53.2 ± 4.3 54.1 ± 4.1 -1.541 0.125 BMI, kg/m 2 24.5 ± 3.3 23.9 ± 3.5 1.269 0.206 Gender 0.416 0.519 Male 62 (60.2) 58 (55.8) - - Female 41 (39.8) 46 (44.2) - - Hypertension history 43 (41.7) 48 (44.4) 0.408 0.523 Diabetes history 35 (34.0) 29 (27.9) 0.901 0.343 ASA classification 1.681 0.711 Ⅰ 34 (33.0) 29 (27.9) - - Ⅱ 57 (55.3) 61 (58.6) - - Ⅲ 12 (11.7) 14 (13.5) - - Laterality 0.826 0.363 Left 59 (57.3) 66 (63.5) - - Right 44 (42.7) 38 (36.5) - - Stone diameter (cm) 1.5 ± 0.5 1.6 ± 0.4 -1.589 0.114 CT value of stone (HU) 1017.5 ± 124.1 996.3 ± 114.9 1.275 0.204 Grade of hydronephrosis 0.642 0.423 None or Mild 66 (64.1) 61 (58.7) - - Moderate or Severe 37 (35.9) 43 (41.3) - - Urine culture 0.166 0.684 Negative 73 (70.9) 71 (68.3) - - Positive 30 (29.1) 33 (31.7) - - Pre-stenting 39 (37.9) 35 (33.6) 0.399 0.527 Upper urinary stone operation histories a 22 (21.3) 27 (26.0) 0.607 0.436 SD = standard deviation; BMI = body mass index; ASA = American Society of Anesthesiologists; CT = computed tomography. a Upper urinary stone operation histories include flexible ureteroscope lithotripsy, percutaneous nephrolithotomy or open surgery for stone. Table 3 Comparisons of surgical outcomes and postoperative clinical characteristics between two groups Variables, mean ± SD or n (%) Study group (n = 103) Control group (n = 104) t/ χ 2 value P value Immediate SFR 84 (81.5) 67 (64.4) 7.695 0.006** Total SFR 93 (90.3) 81 (77.9) 5.944 0.015* Operative time, min 57.1 ± 4.3 62.5 ± 4.9 -8.424 < 0.001** Hemoglobin decrease, g/L 7.2 ± 2.4 7.7 ± 2.1 -1.596 0.112 Postoperative hospital stays, days 1.5 ± 0.3 1.6 ± 0.6 -1.514 0.132 3 months ureteral stricture 1 (1.0) 7 (6.7) 4.621 0.032* Clavien-Dindo 12.121 38.5℃) (Clavien grade Ⅰ) 3 (2.9) 11 (10.6) 4.821 0.028* Low back pain (Clavien grade Ⅰ) 4 (3.9) 14 (13.5) 5.979 0.014* Perirenal hematoma (Clavien grade Ⅱ) 1 (1.3) 8 (7.7) 5.622 0.018* Blood transfusion (Clavien grade Ⅱ) 0 (0.0) 2 (1.9) 2.000 0.157 Urosepsis (Clavien grade Ⅳ) 0 (0.0) 5 (4.8) 5.075 0.024* Stone compositions 0.544 0.909 Calcium oxalate 52 (50.5) 55 (52.9) - - Calcium phosphate 15 (14.6) 13 (12.5) - - Struvite or carbonated apatite 27 (26.2) 29 (27.9) - - Uric acid or cysteine 9 (8.7) 7 (6.7) - - SD= standard deviation; SFR = stone-free rate; QoL = Quality of life; * P < 0.05, ** P < 0.01.; 4 Discussion The retrograde migration of middle and upper ureteral stones during lithotripsy is considered one of the primary factors negatively affecting the SFR in ureteroscopy. The migration of larger stone fragments into blind spots, especially the lower calyces, can reduce SFR and often necessitates additional treatment [ 13 ] . Based on our experience, the primary causes of stone displacement include the retrograde flow of intraoperative perfusion fluid during surgery and the pulse effect of the laser. To address this issue, doctors have adopted various strategies. One most commonly used methods is the placement of a stone occlusion device above the ureteral stone. Yi X et al. reported that ureterolithotripsy combined with a stone occlusion device for in situ lithotripsy was associated with low rates of stone migration, minimal complications, and high SFR [ 14 ] . Additionally, patient positioning may significantly influence stone migration during lithotripsy. Previous prospective, randomized, comparative studies have shown that the reverse Trendelenburg position is a safe and effective surgical method for treating proximal ureteral stones, offering reduced stone migration, higher SFR, shorter operative times, and fewer postoperative complications [ 15 , 16 ] . Despite these strategies, in situ lithotripsy within the ureter still has notable drawbacks [ 17 , 18 ] . First, due to the narrow ureteral lumen, laser lithotripsy can easily damage the surrounding mucosa, increasing the risk of ureteral stricture. Second, in cases involving a bent ureter, the angle for stone fragmentation is severely limited, making the procedure more technically challenging and time-consuming. Lastly, stone fragments migrating into the renal pelvis during lithotripsy can contribute to a low SFR. Therefore, to further explore the efficacy and safety of in situ lithotripsy versus active migration lithotripsy, we conducted this prospective clinical study. Efficacy is the first issue that clinical research must address. Based on the aforementioned considerations, we developed a specific operative strategy. A key component of our approach is active stone migration. We always aim to mobilize the stone into the renal pelvis using the irrigation flow, the tip of the ureteroscope, or a guidewire. A recent meta-analysis reported an overall ureteral stricture rate of 1.9% following ureteroscopy, rising to 2.7% in studies from the past 5 years and up to 4.9% when stones were impacted [ 19 ] . The choice of treatment method is likely the main contributing factor. Our study sought to minimize ureteral trauma by avoiding laser lithotripsy within the ureter itself. Accordingly, at 3 months postoperatively, the ureteral stricture rate in the study group was significantly lower than that in the control group (1.0% vs. 6.7%, P = 0.032). Then, patients in the study group were placed in the Trendelenburg lithotomy position (head down 30 degrees) to facilitate retrograde access and promote stone migration into the upper or middle calyces—areas considered optimal for RIRS. Operating in the renal lower calyx was avoided whenever possible. Fragmenting stones in the renal calyces helps to restrict stone movement, enhances fragmentation efficiency, and improves stone removal. Consequently, our findings demonstrated that the study group had significantly higher immediate and total SFRs than the control group (81.5% vs. 64.4%, P = 0.006; 90.3% vs. 77.9%, P = 0.015, respectively). In addition, with the support of FANS during RIRS, the study group benefited from a clearer surgical field. The balance between irrigation and negative pressure allowed for simultaneous lithotripsy and suction. Consequently, the operative time was significantly shorter in the study group than in the control group (57.1 vs. 62.5 min, P < 0.001). Safety is another critical aspect in clinical research. UTI is one of the most frequent complications following RIRS, with reported incidence ranging from 1.7% to 18.8% [ 20 ] . A major contributing factor is elevated intrarenal pressure (IRP) during surgery. Some studies have shown that applying negative pressure technology in RIRS can reduce infection rates by lowering IRP [ 21 , 22 ] . FANS addresses this issue effectively by passively bending with the fURS to traverse the ureteropelvic junction and reach the renal pelvis and calyces. Our study confirmed that the incidences of fever (> 38.5°C), lower back pain, perirenal hematoma, and urosepsis were significantly lower in the study group than in the control group (2.9% vs. 10.6%, P = 0.028; 3.9% vs. 13.5%, P = 0.014; 1.3% vs. 7.7%, P = 0.018, 0% vs. 4.8%, P = 0.024, respectively). Despite promising results, this study has several limitations. First, the 3-month follow-up period may not be sufficient to detect long-term complications such as delayed ureteral strictures. Second, the study did not include a comprehensive cost-effective analysis, which would have provided valuable insights into the economic implications of FANS use compared with conventional ureteroscopic lithotripsy. Lastly, as a single-center study with a modest sample size, the potential for sampling bias exists. Optimal procedures will likely emerge from extended clinical applications and observations over time. 5 Conclusions Our study provides evidence that the active migration technique, when combined with FANS in RIRS, results in a higher SFR and a lower complication rate than in situ lithotripsy for treating 1–2 cm middle and upper ureteral stones. This technique is safe, effective, and reproducible in clinical practice. However, further validation through large-scale multicenter prospective studies is necessary to substantiate the aforementioned findings. Abbreviations retrograde intrarenal surgery RIRS percutaneous nephrolithotomy PCNL extracorporeal shock wave lithotripsy ESWL European Association of Urology EAU stone-free rate SFR flexible and negative suction ureteral access sheath FANS urinary tract infection UTI plain abdominal radiography of the kidneys, ureters, and bladder KUB intrarenal pressure IRP Declarations Ethics approval and consent to participate All procedures performed in studies involving human participants were in accordance with the ethical standards of Affiliated Jiangning Hospital of Nanjing Medical University (ethics approval number: 2025-03-132-K01) and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The clinical trial registration number for study is ChiCTR2200056402. Consent for publication Informed consent was obtained from all individual participants included in the study. Availability of data and materials The datasets used and analysed during the current study available from the corresponding author on reasonable request. Competing Interests The authors declare that they have no competing financial interests. Funding This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Authors' contributions QL Tang and RZ Tao: Project development. P Liang and XZ Zhou: Data Collection. YP Li, JY Ji and YX Zhang: Data analysis and Manuscript writing. Acknowledgements We thank Dr. Rong-zhen Tao and Prof. Qing-lai Tang for technical assistance and manuscript preparation. References Deguchi R, Yamashita S, Iwahashi Y. The ratio of CT attenuation values of the ureter above/below ureteral stones is a useful preoperative factor for predicting impacted ureteral stones. Urolithiasis. 2022;50(5):643–9. 10.1007/s00240-022-01354-x . Chung DY, Kang DH, Cho KS et al. (2019) Comparison of stone-free rates following shock wave lithotripsy, percutaneous nephrolithotomy, and retrograde intrarenal surgery for treatment of renal stones: A systematic review and network meta-analysis. PLoS One. 21;14(2):e0211316. 10.1371/journal.pone.0211316 Anon. EAU guidelines on urolithiasis - GUIDELINES - uroweb.Uroweb - European association of Urology. Available at: https://uroweb.org/guidelines/urolithiasis/chapter/guidelines . Accessed November 14, 2023. Jayaprakash SP, Thangarasu M, Jain N et al. (2020) In situ Management of Large Upper Ureteric Calculus by Mini-Percutaneous Nephrolithotomy in the Era of Retrograde Intrarenal Surgery. Res Rep Urol. 10;12:633–638. 10.2147/RRU.S280454 Liang H, Liang L, Lin Y, et al. Application of tip-bendable ureteral access sheath in flexible ureteroscopic lithotripsy: an initial experience of 224 cases. BMC Urol. 2023;23(1):175. 10.1186/s12894-023-01347-x . Wang DJ, Liang P, Yang TX et al. (2024) RIRS with FV-UAS vs. MPCNL for 2-3-cm upper urinary tract stones: a prospective study. Urolithiasis. 10;52(1):31. https://doi:10.1007/s00240-024-01539-6 Tang QL, Liang P, Li LH, et al. RIRS with flexible vacuum-assisted UAS versus MPCNL for impacted upper ureteral stones: a prospective, randomized controlled study. Urolithiasis. 2025;53(1):105. 10.1007/s00240-025-01781-6 . Karakan T, Kilinc MF, Demirbas A, et al. Evaluating Ureteral Wall Injuries with Endoscopic Grading System and Analysis of the Predisposing Factors. J Endourol. 2016;30(4):375–8. 10.1089/end.2015.0706 . Dauw CA, Simeon L, Alruwaily AF, et al. Contemporary Practice Patterns of Flexible Ureteroscopy for Treating Renal Stones: Results of a Worldwide Survey. J Endourol. 2015;29(11):1221–30. 10.1089/end.2015.0260 . Mitropoulos D, Artibani W, Biyani CS, et al. Validation of the Clavien-Dindo Grading System in Urology by the European Association of Urology Guidelines Ad Hoc Panel. Eur Urol Focus. 2018;4(4):608–13. 10.1016/j.euf.2017.02.014 . Tao RZ, Tang QL, Zhou S, et al. External physical vibration lithecbole facilitating the expulsion of upper ureteric stones 1.0–2.0 cm after extracorporeal shock wave lithotripsy: a prospective randomized trial. Urolithiasis. 2020;48(1):71–7. 10.1007/s00240-018-1100-8 . Yang J, Tao RZ, Lu P, et al. Efficacy analysis of self-help position therapy after holmium laser lithotripsy via flexible ureteroscopy. BMC Urol. 2018;18(1):33. 10.1186/s12894-018-0348-1 . Legemate JD, Wijnstok NJ, Matsuda T, et al. Characteristics and outcomes of ureteroscopic treatment in 2650 patients with impacted ureteral stones. World J Urol. 2017;35(10):1497–506. 10.1007/s00345-017-2028-2 . Yi X, Li X, Peng K, et al. Stone Occlusion Device with Drainage Function Is Effective in Ureteral Calculi Treatment: A Preliminary Report. Urol Int. 2023;107(6):578–82. 10.1159/000530029 . Pan J, Xue W, Xia L, et al. Ureteroscopic lithotripsy in Trendelenburg position for proximal ureteral calculi: a prospective, randomized, comparative study. Int Urol Nephrol. 2014;46(10):1895–901. 10.1007/s11255-014-0732-z . Yildiz AK, Doluoglu OG, Kacan T, et al. A new position utilizing the effect of gravity in proximal ureteral stones, ureteroscopic lithotripsy in the reverse Trendelenburg position: a prospective, randomized, comparative study. World J Urol. 2023;41(12):3695–703. 10.1007/s00345-023-04654-y . Galal EM, Anwar AZ, El-Bab TK, et al. Retrospective comparative study of rigid and flexible ureteroscopy for treatment of proximal ureteral stones. Int Braz J Urol. 2016;42(5):967–72. 10.1590/S1677-5538.IBJU.2015.0644 . Bulbul E, Tutar O, Gultekin MH, et al. The association between ureteral wall thickness and need for additional procedures after primary ureteroscopy in patients with ureteral stones above the iliac crest. Aktuelle Urol. 2023;54(1):37–43. 10.1055/a-1840-0682 . English. Moretto S, Saita A, Scoffone CM, et al. Ureteral stricture rate after endoscopic treatments for urolithiasis and related risk factors: systematic review and meta-analysis. World J Urol. 2024;42(1):234. 10.1007/s00345-024-04933-2 . Zhang H, Jiang T, Gao R, et al. Risk factors of infectious complications after retrograde intrarenal surgery: a retrospective clinical analysis. J Int Med Res. 2020;48(9):300060520956833. 10.1177/0300060520956833 . Zhu Z, Cui Y, Zeng F, et al. Comparison of suctioning and traditional ureteral access sheath during flexible ureteroscopy in the treatment of renal stones. World J Urol. 2019;37(5):921–9. 10.1007/s00345-018-2455-8 . Deng X, Song L, Xie D, et al. A Novel Flexible Ureteroscopy with Intelligent Control of Renal Pelvic Pressure: An Initial Experience of 93 Cases. J Endourol. 2016;30(10):1067–72. 10.1089/end.2015.0770 . 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-8924143","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":612396687,"identity":"5ba169e1-6a61-45a2-b1e0-5fc52105faf1","order_by":0,"name":"Ping Liang","email":"","orcid":"","institution":"The second Hospital of Nanjing, Affiliated to Nanjing University of Chinese Medicine","correspondingAuthor":false,"prefix":"","firstName":"Ping","middleName":"","lastName":"Liang","suffix":""},{"id":612396688,"identity":"6d7ab04a-2650-443e-9450-cbff4a560d7c","order_by":1,"name":"Qing-lai Tang","email":"","orcid":"","institution":"The Affiliated Jiangning Hospital of Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Qing-lai","middleName":"","lastName":"Tang","suffix":""},{"id":612396689,"identity":"2b461c6b-f81b-4e25-87e9-c97881baaa28","order_by":2,"name":"Jia-yan Ji","email":"","orcid":"","institution":"The Affiliated Jiangning Hospital of Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Jia-yan","middleName":"","lastName":"Ji","suffix":""},{"id":612396690,"identity":"bfbc93cc-377d-47a5-9b75-943a503becf6","order_by":3,"name":"Yu-xin Zhang","email":"","orcid":"","institution":"The Affiliated Jiangning Hospital of Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yu-xin","middleName":"","lastName":"Zhang","suffix":""},{"id":612396691,"identity":"5211fbd0-2fd6-46ef-8db7-72bac588052a","order_by":4,"name":"Yun-peng Li","email":"","orcid":"","institution":"The Affiliated Jiangning Hospital of Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yun-peng","middleName":"","lastName":"Li","suffix":""},{"id":612396692,"identity":"e5e4ecf4-d1ac-451d-8398-47bb86c65210","order_by":5,"name":"Xing-zhu Zhou","email":"","orcid":"","institution":"The Affiliated Jiangning Hospital of Nanjing Medical University","correspondingAuthor":false,"prefix":"","firstName":"Xing-zhu","middleName":"","lastName":"Zhou","suffix":""},{"id":612396693,"identity":"d8431880-0b2c-49c4-80b4-1adbc88a33bc","order_by":6,"name":"Rong-zhen Tao","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5UlEQVRIie3QMWsCMRTA8RyBdHl4a4SiX+FB4UY/S8LJTQp2kQwOBSU3iPv5LW50zPEgU9rZUekXsJtbdW9prptDflOG/EneYyxJHpB4Wju6mu/J/dCdlFnFkwF4TSzwMgdf4in4eDKSsxfKLM/2zawYnje8x8cgIL1awdFVldFvguX1VkVmsQtqPmCAjvxRH56ZDO9t5BVqHSwlx85WRx0EQzmPJFKhA4FZS1AstOV9kikSWJXtLRSsXwJedU1w9yWLUqrgITrLuF7T5WLcRIw/u6+rWY3yevd38gP873qSJEnyqxss4FA/mIZlOQAAAABJRU5ErkJggg==","orcid":"","institution":"The Affiliated Jiangning Hospital of Nanjing Medical University","correspondingAuthor":true,"prefix":"","firstName":"Rong-zhen","middleName":"","lastName":"Tao","suffix":""}],"badges":[],"createdAt":"2026-02-20 09:21:55","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8924143/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8924143/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105641193,"identity":"facd33c8-8c2d-4803-9c33-4bac28979d4e","added_by":"auto","created_at":"2026-03-28 16:26:41","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":122376,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFlowchart for cases selection of the trial outlining enrollment, randomisation, allocation, follow-up, and analysis according to intention-to-treat standards.\u003c/strong\u003e RIRS, Retrograde intrarenal surgery.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8924143/v1/efe17a04c37c89aba7418c68.jpeg"},{"id":105729237,"identity":"f64f24e0-4b91-4360-b08a-c3a1b2403d54","added_by":"auto","created_at":"2026-03-30 11:13:58","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":103258,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eStructural diagrams of the flexible and negative suction ureteral access sheath (FANS).\u003c/strong\u003e(A) Whole view of the FANS; (B) Diagram of the proximal end of the FANS.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8924143/v1/d368145bb3ab5844663b15c1.jpeg"},{"id":105641194,"identity":"303c2551-9a76-4237-9ab6-4751c60bae99","added_by":"auto","created_at":"2026-03-28 16:26:41","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1014394,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSimulation diagrams of the active migration technique combined with the flexible and negative suction ureteral access sheath (FANS) in Retrograde intrarenal surgery (RIRS).\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8924143/v1/f95936c8602e81caa635f58e.png"},{"id":109170357,"identity":"3feb9a7e-7042-42d9-a1bd-6ccafacfc0f5","added_by":"auto","created_at":"2026-05-13 08:47:17","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1346033,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8924143/v1/3fae3c42-f7fb-4173-a790-393bd4c1af84.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Active migration technique versus in situ lithotripsy technique in RIRS for 1-2 cm middle and upper ureteral stones: a prospective, randomized controlled study","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eUreteral stones are a common condition in urology. Compared with lower ureteral stones, the treatment of middle and upper ureteral stones is often more challenging \u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e. Among the various treatment options for ureteral stones measuring 1\u0026ndash;2 cm, retrograde intrarenal surgery (RIRS) has become a widely adopted approach due to its minimally invasive nature compared with percutaneous nephrolithotomy (PCNL) and its greater versatility compared with extracorporeal shock wave lithotripsy (ESWL) \u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e. In line with this, the European Association of Urology (EAU) recommends RIRS as the primary treatment option for ureteral stones\u0026thinsp;\u0026ge;\u0026thinsp;1 cm \u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eMost clinicians are accustomed to using ureteroscopy for in situ lithotripsy. However, due to the narrow lumen and natural curvature of the ureter, the laser fiber often cannot make direct contact with the stone, requiring repeated adjustments in angle to achieve lithotripsy \u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. This not only increases the complexity and duration of the procedure but also easily elevates the risk of ureteral injury. Reported stone-free rates (SFRs) for 1\u0026ndash;2 cm middle and upper ureteral stones treated with ureteroscopy vary widely (45.6%-96.7%), largely depending on the surgical strategy employed \u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. The recent introduction of the flexible and negative suction ureteral access sheath (FANS) in RIRS represents a significant advancement. Studies have shown that combining FANS with RIRS can significantly improve SFR and reduce postoperative complications in patients with upper urinary tract stones \u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn our department, we have optimized the treatment strategy for middle and upper ureteral stones by initially pushing the stones into favorable renal calyces\u0026mdash;typically the upper and middle calyces\u0026mdash;before performing laser lithotripsy. We refer to this approach as the active migration technique. We hypothesize that its advantages include: (1) reducing the need for lithotripsy within the ureter, thereby minimizing ureteral damage; (2) fragmenting stones in a semi-enclosed space, which prevents stone fragments from dispersing throughout the renal pelvis and potentially improves the SFR. To date, no studies have evaluated the use of the active migration technique in combination with FANS for treating middle and upper ureteral stones. Therefore, we conducted a prospective, randomized controlled trial to assess and compare the efficacy and safety of the active migration technique versus the conventional in situ lithotripsy technique in RIRS for patients with 1\u0026ndash;2 cm middle and upper ureteral stones.\u003c/p\u003e"},{"header":"2 Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Study Design and Patients\u003c/h2\u003e \u003cp\u003ePatients with 1-2-cm middle and upper ureteral stones who were referred to our institute were considered for this prospective, randomized controlled study conducted between December 2022 and February 2025. After applying strict inclusion and exclusion criteria, as outlined in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the patients were randomly assigned to two groups by using the envelope method. Finally, 207 patients were enrolled in the study, of which 103 included in the study group received active migration lithotripsy and 104 included in the control group received in situ lithotripsy, which was decided based on power analysis performed to estimate the sample size (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The participants\u0026rsquo; pretreatment evaluation included medical history, physical examination, laboratory investigations (i.e., urine analysis, urine culture and/or sensitivity, complete blood count, blood urea nitrogen, and the serum levels of creatinine, C-reactive protein, and procalcitonin), as well as radiological investigations. Patients with a known urinary tract infection (UTI) received antibiotic treatment until the infection was under control. The study was approved by the clinical research ethics committee of the Affiliated Jiangning Hospital of Nanjing Medical University (ethics approval number: 2025-03-132-K01). Written informed consent was obtained from all participants. The study followed the principles of the Helsinki Declaration.\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\u003eThe inclusion criteria and exclusion criteria in the study\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThe inclusion criteria:\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eThe exclusive criteria:\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePatients\u0026rsquo; age was 18 to 70 years;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUncontrollable UTI and requires\u0026nbsp;drainage;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiagnosed as 1.0\u0026ndash;2.0 cm single middle or upper ureteral stones confirmed by CT;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSevere cardiovascular and cerebrovascular diseases;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo contraindications for surgery;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePregnancy or coagulation disorders;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThe time from diagnosis to surgery was less than one month.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCombining ipsilateral renal stones or bilateral ureteral stones required a one-stage surgery.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbility to provide written informed consent and comply with the trial requirements;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHistory of ureteral stenosis;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAmerican Society of Anesthesiology score 1\u0026ndash;3.\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUnable to understand or comply with trial records.\u003c/p\u003e \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=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Randomization and masking\u003c/h2\u003e \u003cp\u003eParallel randomization was conducted by using a stratified approach in our study. Our center enrolled 207 participants, who were then randomized in a 1:1 ratio to either the study or the control group. The randomization sequence was arranged electronically before patient inclusion. Consecutively numbered and sealed envelopes were used for random sequence allocation and concealment. After subjecting the patients to general anesthesia and before ureteroscopy was entered into the urethra, the sealed envelope was opened by a designated nurse to reveal the specific surgical approach to be undertaken. Subsequently, after the procedure, the same nurse automatically recorded the operative data.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Perioperative and surgical procedures\u003c/h2\u003e \u003cp\u003eAll patients underwent preoperative imaging, including plain abdominal radiography of the kidneys, ureters, and bladder (KUB) and non-contrast CT to evaluate hydronephrosis, as well as to assess the size, location, number, and specific details related to the ureteral stones. Accordingly, preprocedural urine cultures were prepared and used in appropriate antibiotic therapy as per the results of the culture-antibiogram test. Patients showing negative urine cultures were treated with broad-spectrum antibiotics before the surgery (i.e., intravenous cefuroxime 1.5 g or levofloxacin 500 mg, if allergic). Otherwise, the procedures were scheduled once the infection indicators displayed a downward trend after the application of sensitive antibiotics (mainly intravenous piperacillin sodium and tazobactam sodium) and after confirming a negative urine culture. The stone size was defined as the largest diameter of a single stone on preoperative KUB and/or non-contrast CT. All procedures were conducted by two urologists, each with experience in conducting more than 200 RIRS procedures annually. The surgical method for the enrolled patients was randomly selected, thereby excluding any subjective bias.\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.3.1 Study group procedure.\u003c/h2\u003e \u003cp\u003eUnder general anesthesia, patients were placed in the Trendelenburg lithotomy position (head down by 30 degrees) for retrograde endoscopic access. A ureteroscopy (STORZ, 8/9.8-Fr) was performed to identify the location of stone obstruction, and the stone was pushed back into the renal pelvis under water flow, the tip of the ureteroscope or guidewire (Bard, USA). Then, a loach guidewire was introduced to access the upper urinary tract, followed by the placement of a 12/14-Fr or 11/13-Fr FANS (length: 40 cm for females; 50 cm for males) (Wellead Medical, Guangdong, China) into the upper affected ureter (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The advantage offered by this sheath was that the 3-mm soft tip was designed without a metal spring coil, which provided optimal protection for the ureter mucosa \u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. Occurrence of ureteral stenosis or distortion during surgery could lead to the failure of FANS implantation; therefore, balloon dilation was attempted as the first line of approach. In cases not feasible for dilation, only a double-J stent was inserted for ureteral expansion. A 7.5-Fr disposable electronic flexible ureteroscope (fURS) (Pusen Medical, Guangdong, China) was then inserted through the FANS and the FANS was adjusted to encase the stone within the renal collecting system (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). We usually set the fluid irrigation flow to 80\u0026ndash;100 mL/min and a negative pressure suction to 85\u0026ndash;90 mmHg to obtain a clear surgical view. The lithotripsy process was performed using a holmium laser with a 200-\u0026micro;m laser fiber under an energy of (0.6\u0026ndash;0.8 J) * (20\u0026ndash;30 Hz). Small fragments were automatically aspirated through the gap between the fURS and FANS, whereas larger fragments required the fURS to be repeatedly inserted and withdrawn slowly under continuous suction from the body (\u003cb\u003eSupplementary Video 1\u003c/b\u003e). At the end of the procedure, the fURS was directed toward the collecting system to retrieve any remaining large stone fragments. The FANS and fURS were removed under direct visualization to document and evaluate any ureteral injury \u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e. A 6-Fr double-J stent (Bard, USA) was placed in all patients postoperatively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.3.2 Control group procedure.\u003c/h2\u003e \u003cp\u003eGeneral anesthesia was administered, and the lithotomy position was used for each patient in this group. A ureteroscopy was performed to retrogradely access the ureter until reaching the stone, and the surroundings of the stone were observed. We usually place a stone occlusion device (IVX-SC10; Innovex Medical, Shanghai) along the gap between the stone and the ureteral mucosa above the stone. Presently, the stone was fragmented with a holmium laser using a 200-\u0026micro;m laser fiber (with energy setting\u0026thinsp;\u0026lt;\u0026thinsp;15 W). Then, the stone fragments were removed using a nitinol stone basket (Cook Medical, USA). Similarly, ureteroscopy was performed to examine the entire ureter, and a 6-Fr double-J stent was indwelt.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Postoperative follow-up\u003c/h2\u003e \u003cp\u003eThe level of white blood cell counts, C-reactive protein, and procalcitonin at 2-h postoperatively was monitored to screen out serious UTI. Then, 1-mm-thick sections from all patients were subjected to ultra-low-dose, non-contrast CT scanning on the first postoperative day and then at 4 weeks after the surgery to evaluate the immediate and total SFR. Two groups of patients were discharged within 48 h of the surgery if they did not experience any significant discomfort. Every patient received health education before discharge, including recommendations related to precautions, follow-up dates, and emergency contact information. Double-J stents were removed within 4 weeks of the surgery. Meanwhile, the stone composition analyses were performed for all patients to obtain a reference for metabolic analysis and subsequent prevention.\u003c/p\u003e \u003cp\u003eStone-free status was defined as the complete absence of residual stone fragments or the presence of clinically insignificant fragments measuring\u0026thinsp;\u0026le;\u0026thinsp;2 mm, asymptomatic, non-obstructive, and non-infectious \u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. The primary study outcome was the SFR on the first postoperative day. The secondary outcomes included the total SFR 4 weeks postoperatively (evaluated through ultra-low-dose CT), operative time, reduction in the hemoglobin levels, the length of postoperative hospital stay, the incidence of ureteral stricture at 3-month postoperatively, and any surgery-related complications.\u003c/p\u003e \u003cp\u003eThe operative time was calculated from the time since the ureteroscope was inserted into the urethra up to the time when the double-J tube was placed. Reduction in the hemoglobin levels was deemed indicative of the difference between preoperative hemoglobin levels and the 2-h postoperative hemoglobin level. The length of postoperative hospital stay was counted from the day of surgery to the time of discharge. Importantly, postoperative hydronephrosis was monitored, particularly for ureteral stone patients. Regular urinary ultrasound examinations were conducted for all patients on a monthly basis. Patients were asked to undertake IVU or enhanced CT and provided a follow-up treatment plan if their hydronephrosis had significantly worsened relative to their preoperative imaging at 3 months postoperatively. Postoperative complications were classified using the modified Clavien grading system, including fever (\u0026ge;\u0026thinsp;38.5℃), lower back pain, perirenal hematoma, blood transfusion, and urosepsis \u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e. For patients with residual stones, additional auxiliary procedures were performed at least 4 weeks after the surgery, including external physical vibration lithotripsy, ESWL, or positional therapy, as deemed appropriate \u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Statistical analysis\u003c/h2\u003e \u003cp\u003eStatistical analysis was conducted using IBM SPSS Statistics for Windows, Version 22.0 (IBM Corp., Armonk, NY, USA). Continuous variables were reported as the means\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviations. The independent samples \u003cem\u003et\u003c/em\u003e-test was performed to compare the patient demographics, follow-up data, and surgical outcomes between the groups, whereas the Shapiro\u0026ndash;Wilk test was performed to assess the normality of the initial data. For categorical variables, including other pre- and postoperative clinical characteristics, comparisons were made using the Chi-squared test. \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered to indicate statistical significance.\u003c/p\u003e \u003c/div\u003e"},{"header":"3 Results","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Demographics and preoperative clinical characteristics\u003c/h2\u003e \u003cp\u003eIn total, 207 patients were randomly assigned to either the study group (n\u0026thinsp;=\u0026thinsp;103) or the control group (n\u0026thinsp;=\u0026thinsp;104). No significant differences in baseline demographics or preoperative clinical characteristics were noted between the two groups \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. The mean stone size was 1.5 cm in the study group and 1.6 cm in the control group. Both groups were also comparable in terms of age, body mass index, sex ratio, history of hypertension or diabetes, ASA classification, stone laterality, stone composition, hydronephrosis grade, urine culture results, and history of previous upper urinary stone surgeries (all \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Postoperative clinical characteristics\u003c/h2\u003e \u003cp\u003ePostoperative clinical outcomes are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The mean decrease in hemoglobin and length of postoperative hospital stay did not significantly differ between the two groups (both \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). However, the operative time was significantly shorter in the study group than in the control group (57.1 vs. 62.5 min, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The study group also had significantly higher immediate and total SFRs (81.5% vs. 64.4%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.006, 90.3% vs. 77.9%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.015, respectively). At 3 months postoperatively, ureteral stricture was observed in seven patients in the control group compared with one patient in the study group\u0026mdash;a statistically significant difference (6.7% vs. 1.0%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032).\u003c/p\u003e \u003cp\u003eRegarding postoperative safety, the overall complication rate was significantly lower in the study group than in the control group (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Specific complications such as fever\u0026thinsp;\u0026gt;\u0026thinsp;38.5\u0026deg;C (2.9% vs. 10.6%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.028), lower back pain (3.9% vs. 13.5%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014), perirenal hematoma (1.3% vs. 7.7%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.018), and urosepsis (0% vs. 4.8%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.024) were significantly more frequent in the control group. Blood transfusions were required in two patients in the control group, but in none in the study group, although this difference between the two groups was not statistically significant (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Postoperative stone composition analysis revealed no significant differences between the two groups (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\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\u003eComparisons of patients\u0026rsquo; demographics and preoperative clinical characteristics between two groups\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\u003eVariables, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD or \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStudy group (n\u0026thinsp;=\u0026thinsp;103)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eControl group (n\u0026thinsp;=\u0026thinsp;104)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et/\u003cem\u003eχ\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge, years\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e53.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e54.1\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-1.541\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.125\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBMI, kg/m\u003c/b\u003e\u003csup\u003e\u003cb\u003e2\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23.9\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.269\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.206\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGender\u003c/b\u003e\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 \u003cp\u003e0.416\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.519\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e62 (60.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e58 (55.8)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41 (39.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46 (44.2)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHypertension history\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e43 (41.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e48 (44.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.408\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.523\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDiabetes history\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e35 (34.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29 (27.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.901\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.343\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eASA classification\u003c/b\u003e\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 \u003cp\u003e1.681\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.711\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eⅠ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e34 (33.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29 (27.9)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eⅡ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57 (55.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e61 (58.6)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12 (11.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14 (13.5)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLaterality\u003c/b\u003e\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 \u003cp\u003e0.826\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.363\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLeft\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59 (57.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e66 (63.5)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e44 (42.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38 (36.5)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eStone diameter (cm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-1.589\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.114\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCT value of stone (HU)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1017.5\u0026thinsp;\u0026plusmn;\u0026thinsp;124.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e996.3\u0026thinsp;\u0026plusmn;\u0026thinsp;114.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.275\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.204\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGrade of hydronephrosis\u003c/b\u003e\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 \u003cp\u003e0.642\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.423\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNone or Mild\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e66 (64.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e61 (58.7)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModerate or Severe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37 (35.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e43 (41.3)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eUrine culture\u003c/b\u003e\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 \u003cp\u003e0.166\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.684\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNegative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e73 (70.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e71 (68.3)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePositive\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30 (29.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33 (31.7)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePre-stenting\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e39 (37.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35 (33.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.399\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.527\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eUpper urinary stone operation histories\u003c/b\u003e \u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (21.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27 (26.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.607\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.436\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\u003eSD\u0026thinsp;=\u0026thinsp;standard deviation; BMI\u0026thinsp;=\u0026thinsp;body mass index; ASA\u0026thinsp;=\u0026thinsp;American Society of Anesthesiologists; CT\u0026thinsp;=\u0026thinsp;computed tomography.\u003c/p\u003e \u003cp\u003e \u003csup\u003ea\u003c/sup\u003e Upper urinary stone operation histories include flexible ureteroscope lithotripsy, percutaneous nephrolithotomy or open surgery for stone.\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\u003eComparisons of surgical outcomes and postoperative clinical characteristics between two groups\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=\"char\" char=\".\" 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\u003eVariables, mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD or \u003cem\u003en\u003c/em\u003e (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStudy group (n\u0026thinsp;=\u0026thinsp;103)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eControl group (n\u0026thinsp;=\u0026thinsp;104)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003et/\u003cem\u003eχ\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eImmediate SFR\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e84 (81.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e67 (64.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.695\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.006**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTotal SFR\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e93 (90.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e81 (77.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.944\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.015*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOperative time, min\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e57.1\u0026thinsp;\u0026plusmn;\u0026thinsp;4.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e62.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-8.424\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHemoglobin decrease, g/L\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-1.596\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.112\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePostoperative hospital stays, days\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-1.514\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.132\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3 months ureteral stricture\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1 (1.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7 (6.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.621\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.032*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eClavien-Dindo\u003c/b\u003e\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 \u003cp\u003e12.121\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade Ⅰ-Ⅱ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5 (4.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e17 (16.3)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade Ⅲ-Ⅳ\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0 (0.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5 (4.8)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eComplications\u003c/b\u003e\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\u003eFever (\u0026gt;\u0026thinsp;38.5℃) (Clavien grade Ⅰ)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3 (2.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11 (10.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.821\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.028*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLow back pain (Clavien grade Ⅰ)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4 (3.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e14 (13.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.979\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.014*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePerirenal hematoma (Clavien grade Ⅱ)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1 (1.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8 (7.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.622\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.018*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBlood transfusion (Clavien grade Ⅱ)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0 (0.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2 (1.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.157\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUrosepsis (Clavien grade Ⅳ)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0 (0.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5 (4.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.075\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.024*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eStone compositions\u003c/b\u003e\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 \u003cp\u003e0.544\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.909\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalcium oxalate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e52 (50.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e55 (52.9)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalcium phosphate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15 (14.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e13 (12.5)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStruvite or carbonated\u0026nbsp;apatite\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e27 (26.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e29 (27.9)\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 \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUric acid or cysteine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e9 (8.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7 (6.7)\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 \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eSD= standard deviation; SFR\u0026thinsp;=\u0026thinsp;stone-free rate; QoL\u0026thinsp;=\u0026thinsp;Quality of life;\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e* \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, ** \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01.;\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4 Discussion","content":"\u003cp\u003eThe retrograde migration of middle and upper ureteral stones during lithotripsy is considered one of the primary factors negatively affecting the SFR in ureteroscopy. The migration of larger stone fragments into blind spots, especially the lower calyces, can reduce SFR and often necessitates additional treatment \u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e. Based on our experience, the primary causes of stone displacement include the retrograde flow of intraoperative perfusion fluid during surgery and the pulse effect of the laser. To address this issue, doctors have adopted various strategies. One most commonly used methods is the placement of a stone occlusion device above the ureteral stone. Yi X et al. reported that ureterolithotripsy combined with a stone occlusion device for in situ lithotripsy was associated with low rates of stone migration, minimal complications, and high SFR \u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e. Additionally, patient positioning may significantly influence stone migration during lithotripsy. Previous prospective, randomized, comparative studies have shown that the reverse Trendelenburg position is a safe and effective surgical method for treating proximal ureteral stones, offering reduced stone migration, higher SFR, shorter operative times, and fewer postoperative complications \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e. Despite these strategies, in situ lithotripsy within the ureter still has notable drawbacks \u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. First, due to the narrow ureteral lumen, laser lithotripsy can easily damage the surrounding mucosa, increasing the risk of ureteral stricture. Second, in cases involving a bent ureter, the angle for stone fragmentation is severely limited, making the procedure more technically challenging and time-consuming. Lastly, stone fragments migrating into the renal pelvis during lithotripsy can contribute to a low SFR. Therefore, to further explore the efficacy and safety of in situ lithotripsy versus active migration lithotripsy, we conducted this prospective clinical study.\u003c/p\u003e \u003cp\u003eEfficacy is the first issue that clinical research must address. Based on the aforementioned considerations, we developed a specific operative strategy. A key component of our approach is active stone migration. We always aim to mobilize the stone into the renal pelvis using the irrigation flow, the tip of the ureteroscope, or a guidewire. A recent meta-analysis reported an overall ureteral stricture rate of 1.9% following ureteroscopy, rising to 2.7% in studies from the past 5 years and up to 4.9% when stones were impacted \u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e. The choice of treatment method is likely the main contributing factor. Our study sought to minimize ureteral trauma by avoiding laser lithotripsy within the ureter itself. Accordingly, at 3 months postoperatively, the ureteral stricture rate in the study group was significantly lower than that in the control group (1.0% vs. 6.7%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032).\u003c/p\u003e \u003cp\u003eThen, patients in the study group were placed in the Trendelenburg lithotomy position (head down 30 degrees) to facilitate retrograde access and promote stone migration into the upper or middle calyces\u0026mdash;areas considered optimal for RIRS. Operating in the renal lower calyx was avoided whenever possible. Fragmenting stones in the renal calyces helps to restrict stone movement, enhances fragmentation efficiency, and improves stone removal. Consequently, our findings demonstrated that the study group had significantly higher immediate and total SFRs than the control group (81.5% vs. 64.4%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.006; 90.3% vs. 77.9%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.015, respectively). In addition, with the support of FANS during RIRS, the study group benefited from a clearer surgical field. The balance between irrigation and negative pressure allowed for simultaneous lithotripsy and suction. Consequently, the operative time was significantly shorter in the study group than in the control group (57.1 vs. 62.5 min, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003cp\u003eSafety is another critical aspect in clinical research. UTI is one of the most frequent complications following RIRS, with reported incidence ranging from 1.7% to 18.8% \u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e. A major contributing factor is elevated intrarenal pressure (IRP) during surgery. Some studies have shown that applying negative pressure technology in RIRS can reduce infection rates by lowering IRP \u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. FANS addresses this issue effectively by passively bending with the fURS to traverse the ureteropelvic junction and reach the renal pelvis and calyces. Our study confirmed that the incidences of fever (\u0026gt;\u0026thinsp;38.5\u0026deg;C), lower back pain, perirenal hematoma, and urosepsis were significantly lower in the study group than in the control group (2.9% vs. 10.6%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.028; 3.9% vs. 13.5%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014; 1.3% vs. 7.7%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.018, 0% vs. 4.8%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.024, respectively).\u003c/p\u003e \u003cp\u003eDespite promising results, this study has several limitations. First, the 3-month follow-up period may not be sufficient to detect long-term complications such as delayed ureteral strictures. Second, the study did not include a comprehensive cost-effective analysis, which would have provided valuable insights into the economic implications of FANS use compared with conventional ureteroscopic lithotripsy. Lastly, as a single-center study with a modest sample size, the potential for sampling bias exists. Optimal procedures will likely emerge from extended clinical applications and observations over time.\u003c/p\u003e"},{"header":"5 Conclusions","content":"\u003cp\u003eOur study provides evidence that the active migration technique, when combined with FANS in RIRS, results in a higher SFR and a lower complication rate than in situ lithotripsy for treating 1\u0026ndash;2 cm middle and upper ureteral stones. This technique is safe, effective, and reproducible in clinical practice. However, further validation through large-scale multicenter prospective studies is necessary to substantiate the aforementioned findings.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eretrograde intrarenal surgery RIRS\u003c/p\u003e \u003cp\u003epercutaneous nephrolithotomy PCNL\u003c/p\u003e \u003cp\u003eextracorporeal shock wave lithotripsy ESWL\u003c/p\u003e \u003cp\u003eEuropean Association of Urology EAU\u003c/p\u003e \u003cp\u003estone-free rate SFR\u003c/p\u003e \u003cp\u003eflexible and negative suction ureteral access sheath FANS\u003c/p\u003e \u003cp\u003eurinary tract infection UTI\u003c/p\u003e \u003cp\u003eplain abdominal radiography of the kidneys, ureters, and bladder KUB\u003c/p\u003e \u003cp\u003eintrarenal pressure IRP\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll procedures performed in studies involving human participants were in accordance with the ethical standards of Affiliated Jiangning Hospital of Nanjing Medical University (ethics approval number: 2025-03-132-K01) and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The clinical trial registration number for study is ChiCTR2200056402.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eInformed consent was obtained from all individual participants included in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analysed during the current study available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing financial interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eQL Tang and RZ Tao: Project development.\u003c/p\u003e\n\u003cp\u003eP Liang and XZ Zhou: Data Collection.\u003c/p\u003e\n\u003cp\u003eYP Li, JY Ji and YX Zhang: Data analysis and Manuscript writing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank Dr. Rong-zhen Tao and Prof. Qing-lai Tang for technical assistance and manuscript preparation.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDeguchi R, Yamashita S, Iwahashi Y. The ratio of CT attenuation values of the ureter above/below ureteral stones is a useful preoperative factor for predicting impacted ureteral stones. Urolithiasis. 2022;50(5):643\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00240-022-01354-x\u003c/span\u003e\u003cspan address=\"10.1007/s00240-022-01354-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChung DY, Kang DH, Cho KS et al. (2019) Comparison of stone-free rates following shock wave lithotripsy, percutaneous nephrolithotomy, and retrograde intrarenal surgery for treatment of renal stones: A systematic review and network meta-analysis. PLoS One. 21;14(2):e0211316. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1371/journal.pone.0211316\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0211316\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnon. EAU guidelines on urolithiasis - GUIDELINES - uroweb.Uroweb - European association of Urology. Available at: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://uroweb.org/guidelines/urolithiasis/chapter/guidelines\u003c/span\u003e\u003cspan address=\"https://uroweb.org/guidelines/urolithiasis/chapter/guidelines\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Accessed November 14, 2023.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJayaprakash SP, Thangarasu M, Jain N et al. (2020) In situ Management of Large Upper Ureteric Calculus by Mini-Percutaneous Nephrolithotomy in the Era of Retrograde Intrarenal Surgery. Res Rep Urol. 10;12:633\u0026ndash;638. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.2147/RRU.S280454\u003c/span\u003e\u003cspan address=\"10.2147/RRU.S280454\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiang H, Liang L, Lin Y, et al. Application of tip-bendable ureteral access sheath in flexible ureteroscopic lithotripsy: an initial experience of 224 cases. BMC Urol. 2023;23(1):175. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12894-023-01347-x\u003c/span\u003e\u003cspan address=\"10.1186/s12894-023-01347-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang DJ, Liang P, Yang TX et al. (2024) RIRS with FV-UAS vs. MPCNL for 2-3-cm upper urinary tract stones: a prospective study. Urolithiasis. 10;52(1):31. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi:10.1007/s00240-024-01539-6\u003c/span\u003e\u003cspan address=\"https://doi:10.1007/s00240-024-01539-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTang QL, Liang P, Li LH, et al. RIRS with flexible vacuum-assisted UAS versus MPCNL for impacted upper ureteral stones: a prospective, randomized controlled study. Urolithiasis. 2025;53(1):105. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00240-025-01781-6\u003c/span\u003e\u003cspan address=\"10.1007/s00240-025-01781-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKarakan T, Kilinc MF, Demirbas A, et al. Evaluating Ureteral Wall Injuries with Endoscopic Grading System and Analysis of the Predisposing Factors. J Endourol. 2016;30(4):375\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1089/end.2015.0706\u003c/span\u003e\u003cspan address=\"10.1089/end.2015.0706\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDauw CA, Simeon L, Alruwaily AF, et al. Contemporary Practice Patterns of Flexible Ureteroscopy for Treating Renal Stones: Results of a Worldwide Survey. J Endourol. 2015;29(11):1221\u0026ndash;30. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1089/end.2015.0260\u003c/span\u003e\u003cspan address=\"10.1089/end.2015.0260\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMitropoulos D, Artibani W, Biyani CS, et al. Validation of the Clavien-Dindo Grading System in Urology by the European Association of Urology Guidelines Ad Hoc Panel. Eur Urol Focus. 2018;4(4):608\u0026ndash;13. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.euf.2017.02.014\u003c/span\u003e\u003cspan address=\"10.1016/j.euf.2017.02.014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTao RZ, Tang QL, Zhou S, et al. External physical vibration lithecbole facilitating the expulsion of upper ureteric stones 1.0\u0026ndash;2.0 cm after extracorporeal shock wave lithotripsy: a prospective randomized trial. Urolithiasis. 2020;48(1):71\u0026ndash;7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00240-018-1100-8\u003c/span\u003e\u003cspan address=\"10.1007/s00240-018-1100-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang J, Tao RZ, Lu P, et al. Efficacy analysis of self-help position therapy after holmium laser lithotripsy via flexible ureteroscopy. BMC Urol. 2018;18(1):33. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12894-018-0348-1\u003c/span\u003e\u003cspan address=\"10.1186/s12894-018-0348-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLegemate JD, Wijnstok NJ, Matsuda T, et al. Characteristics and outcomes of ureteroscopic treatment in 2650 patients with impacted ureteral stones. World J Urol. 2017;35(10):1497\u0026ndash;506. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00345-017-2028-2\u003c/span\u003e\u003cspan address=\"10.1007/s00345-017-2028-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYi X, Li X, Peng K, et al. Stone Occlusion Device with Drainage Function Is Effective in Ureteral Calculi Treatment: A Preliminary Report. Urol Int. 2023;107(6):578\u0026ndash;82. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1159/000530029\u003c/span\u003e\u003cspan address=\"10.1159/000530029\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePan J, Xue W, Xia L, et al. Ureteroscopic lithotripsy in Trendelenburg position for proximal ureteral calculi: a prospective, randomized, comparative study. Int Urol Nephrol. 2014;46(10):1895\u0026ndash;901. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s11255-014-0732-z\u003c/span\u003e\u003cspan address=\"10.1007/s11255-014-0732-z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYildiz AK, Doluoglu OG, Kacan T, et al. A new position utilizing the effect of gravity in proximal ureteral stones, ureteroscopic lithotripsy in the reverse Trendelenburg position: a prospective, randomized, comparative study. World J Urol. 2023;41(12):3695\u0026ndash;703. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00345-023-04654-y\u003c/span\u003e\u003cspan address=\"10.1007/s00345-023-04654-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGalal EM, Anwar AZ, El-Bab TK, et al. Retrospective comparative study of rigid and flexible ureteroscopy for treatment of proximal ureteral stones. Int Braz J Urol. 2016;42(5):967\u0026ndash;72. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1590/S1677-5538.IBJU.2015.0644\u003c/span\u003e\u003cspan address=\"10.1590/S1677-5538.IBJU.2015.0644\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBulbul E, Tutar O, Gultekin MH, et al. The association between ureteral wall thickness and need for additional procedures after primary ureteroscopy in patients with ureteral stones above the iliac crest. Aktuelle Urol. 2023;54(1):37\u0026ndash;43. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1055/a-1840-0682\u003c/span\u003e\u003cspan address=\"10.1055/a-1840-0682\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. English.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoretto S, Saita A, Scoffone CM, et al. Ureteral stricture rate after endoscopic treatments for urolithiasis and related risk factors: systematic review and meta-analysis. World J Urol. 2024;42(1):234. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00345-024-04933-2\u003c/span\u003e\u003cspan address=\"10.1007/s00345-024-04933-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang H, Jiang T, Gao R, et al. Risk factors of infectious complications after retrograde intrarenal surgery: a retrospective clinical analysis. J Int Med Res. 2020;48(9):300060520956833. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1177/0300060520956833\u003c/span\u003e\u003cspan address=\"10.1177/0300060520956833\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhu Z, Cui Y, Zeng F, et al. Comparison of suctioning and traditional ureteral access sheath during flexible ureteroscopy in the treatment of renal stones. World J Urol. 2019;37(5):921\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00345-018-2455-8\u003c/span\u003e\u003cspan address=\"10.1007/s00345-018-2455-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDeng X, Song L, Xie D, et al. A Novel Flexible Ureteroscopy with Intelligent Control of Renal Pelvic Pressure: An Initial Experience of 93 Cases. J Endourol. 2016;30(10):1067\u0026ndash;72. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1089/end.2015.0770\u003c/span\u003e\u003cspan address=\"10.1089/end.2015.0770\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\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":"Retrograde intrarenal surgery, Flexible and negative suction ureteral access sheath, Ureteral stones, Stone-free rates, Active migration technique","lastPublishedDoi":"10.21203/rs.3.rs-8924143/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8924143/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTo observe the efficacy and safety of the active migration technique and in situ lithotripsy technique in retrograde intrarenal surgery (RIRS) for patients with 1\u0026ndash;2 cm middle and upper ureteral stones. 207 patients were enrolled in the study, of which 103 included in the study group received active migration lithotripsy and 104 included in the control group received in situ lithotripsy. The primary study outcome was the stone-free rate (SFR) on the first postoperative day. Secondary outcomes included the total SFR 4 weeks postoperatively, operative time, reduction in the hemoglobin levels, the length of postoperative hospital stay, the incidence of ureteral stricture at 3-month postoperatively, and any surgery-related complications. There was no obvious difference between two groups in patients\u0026rsquo; demographics and preoperative clinical characteristics (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The operative time was significantly shorter in the study group than in the control group (57.1 vs. 62.5 min, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The study group also had significantly higher immediate and total SFRs (81.5% vs. 64.4%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.006, 90.3% vs. 77.9%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.015, respectively). At 3 months postoperatively, the incidence of ureteral stricture in the study was statistically lower than in the control group (1.0% vs. 6.7%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032). Notablely, the overall complication rate was significantly lower in the study group than in the control group (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Our study provides evidence that the active migration technique, when combined with flexible and negative suction ureteral access sheath (FANS) in RIRS, results in a higher SFR and a lower complication rate than in situ lithotripsy for treating 1\u0026ndash;2 cm middle and upper ureteral stones. The protocol for this study has been accepted by the Chinese Clinical Trial Registry (The registration number: ChiCTR2200056402; Date of registration: 03-06-2022).\u003c/p\u003e","manuscriptTitle":"Active migration technique versus in situ lithotripsy technique in RIRS for 1-2 cm middle and upper ureteral stones: a prospective, randomized controlled study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-28 16:26:31","doi":"10.21203/rs.3.rs-8924143/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":"ce029855-3b29-4f0a-b86b-91cea350ad1a","owner":[],"postedDate":"March 28th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Withdrawn","date":"2026-05-13T08:31:11+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-05-13T08:45:05+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-28 16:26:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8924143","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8924143","identity":"rs-8924143","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}