First Worldwide Multicentric Series of Mini-Ecirs in Children: Outcomes from two Tertiary Endourology Centers.

Introduction: Endoscopic combined intrarenal surgery (ECIRS) is a combination of both retrograde and antegrade approaches for treatment of large or complex renal stones in one procedure, that are currently being treated with multiple tracts or sessions of percutaneous nephrolithotomy, increasing the complications. The aim of our study is to describe the clinical outcomes of Mini-ECIRS in a pediatric population. Material and Methods: A retrospective study was performed in pediatric patients with lithiasis disease treated with mini-ECIRS between 2006 and 2023 in 2 referral centers in Europe. Demographic data, clinical data, stone size and location, laser settings, intraoperative variables, stone-free rate (SFR) and complications were collected. Pearson's chi-squared test, Fishers test and logistic regression, were performed. Results: A total of 32 mini-ECIRS were included. The mean age was 9,8 years, 56.3% girls. The mean size and volume of the stone were 21.5mm and 3298, 2mm3, 53.1% were multiple. Ureteral access sheath was used in 93.8% of the surgeries and only 37.5% had preoperative JJ stent. 53.1% of percutaneous access were with 14 Fr sheath. High power laser was the most frequent energy source for lithotripsy, including thulium fiber laser. The mean operative time was 166,6 minutes. There was one perforation of the collecting system that was managed with JJ stent and in the postoperative period 81.2% of the patients had no complications. Three presented fever, 1 developed urinary sepsis, and 1 required reintervention. The SFR was 75% and the size, volume, hardness, and complexity of the lithiasis, as well as the non-use of lithotripsy in the retrograde approach were statistically significant in decreasing the success of the surgery. Conclusions: ECIRS is a feasible, safe, and efficient procedure in children with complex renal lithiasis, decreasing the number of procedures needed for stone free. Multicenter studies are required to validate these results on a population scale.

Endoscopic combined intrarenal surgery versus percutaneuos nephrolithotomy for complex pediatric stone disease: A comparative analysis of efficacy and safety.

INTRODUCTION: Decision-making for complex pediatric urinary system stone disease is still a challenge for pediatric urologists. The interest in supine percutaneous nephrolithotomy (PCNL) is increasing among centers to achieve high surgical success rates with less morbidity. Despite advanced retrograde intrarenal surgery armamentarium, percutaneous approaches remain the first-line surgical treatment modality for >2 cm and complex renal stones. There are no comparative studies yet in the literature for pediatric endoscopic combined intrarenal surgery (ECIRS) OBJECTIVE: In this study, we aimed to contribute to the literature by evaluating the safety and efficacy of ECIRS by comparing it with PCNL. STUDY DESIGN: Patients under 18 years of age who underwent PCNL and ECIRS for urinary tract stone disease at our Pediatric Urology department between 2012 and 2024 were included. Preoperative (demographic characteristics, stone characteristics, biochemical parameters), perioperative (duration of surgery, number of accesses, lasing and fluoroscopy times, endoscopic and fluoroscopic stone-free rates) and postoperative (hospital stay, urinary tract infection, complication and radiological stone-free rates) parameters were retrospectively evaluated. RESULTS: A total of 68 children [28 (41%) girls and 40 (59%) boys] aged 5 (0-17) years were included in the study. ECIRS was performed in 19 (28%), supine in 28 (41%) and prone PCNL in 21 (30%) patients. Age (p = 0.029), Guy's stone score (p < 0.001), S.T.O.N.E. (p < 0.001), and Seoul National University Renal Stone Complexity (S-ReSC) scores (p = 0.001) for preoperative parameters were found to be higher in ECIRS group over both PCNL methods (Summary Table). However, Clinical Research Office of the Endourological Society (CROES) score was seen lower for ECIRS group patients compared to other groups (p = 0.028). Surgery time (in favor of supine over prone PCNL), fluoroscopy time (in favor of ECIRS and Supine PCNL over Prone PCNL), preferred laser type (prone PCNL group was mostly performed with holmium laser, whereas other groups were balanced between Holmium and Thulium Fiber Laser) and exit strategy (the preferred exit strategy was DJ Stent in most of the ECIRS patients, whereas nephrostomy tube was used in some of the PCNL group) showed significant difference among the groups as perioperative parameters (p = 0.042, <0.001, <0.001, <0.001, respectively). Surgery time was lower for supine PCNL compared to prone PCNL. For postoperative parameters, stone-free rates, complication rates and urinary tract infections were similar between the 3 groups, while a difference was detected in terms of length of hospital stay in favor of ECIRS over both supine and prone PCNL (p = 0.006). DISCUSSION: The current trial suggests that stone-free and complication rates of ECIRS and supine PCNL were similar in the pediatric complex stone patients. Although, the stones in the ECIRS group we found to be more complex. Also, ECIRS was superior to PCNL in terms of fluoroscopy exposure and hospital stay. CONCLUSION: With the widespread use of new generation ureteral access sheaths and flexible ureterorenoscopes, ECIRS may have an important role in treatment of complex pediatric kidney stones.

Effect of nephrostomy sheath size on renal pelvic pressure during endoscopic combined intrarenal surgery: artificial kidney model study.

BACKGROUND: This study aimed to evaluate the intrarenal pelvic pressure in endoscopic combined intrarenal surgery using an artificial kidney model. METHODS: An artificial kidney model was created using the Urovac evacuator™. Four sizes of nephrostomy sheaths (MIP-L: 25/26 Fr, MIP-M: 16.5/17.5 Fr, MIP-S: 11/12 Fr, MIP-XS: 8.5/9.5 Fr) and two sizes of ureteral access sheaths (12/14 Fr and 10/12 Fr) were installed into the model. For each combination of nephrostomy and ureteral access sheath, renal pelvic pressure was measured with and without insertion of the retrograde flexible ureteroscope. Irrigation from the nephroscope was adjusted to 40-160 mmHg using an automatic irrigation device, and the irrigation of the ureteroscope was by spontaneous dripping at 80 cmH2O. Conditions were measured six times, and the renal pelvic pressure was compared in different conditions. RESULTS: Without ureteroscope insertion through the ureteral access sheath, the renal pelvic pressure never exceeded 30 mmHg. Meanwhile, when the ureteroscope was inserted, the renal pelvic pressure increased as the nephrostomy sheath and ureteral access sheath became narrower and as the irrigation pressure increased. Intrarenal pelvic pressure exceeded 30 mmHg when the irrigation pressure was increased in 12/14 Fr ureteral access sheath when MIP-XS was used, and in 10/12 Fr ureteral access sheath when MIP-XS and MIP-S were used. CONCLUSIONS: The use of a thin nephrostomy sheath in endoscopic combined intrarenal surgery can lead to increased intrarenal pelvic pressure. Although our results are from an artificial kidney model, special care is suggested to be required when using a retrograde flexible ureteroscope simultaneously in treatment of patients.

Retrograde intrarenal surgery using the ILY robotic flexible ureteroscope: a single centre experience.

Introduction: The ILY robotic flexible ureteroscope has been introduced in order to improve intraoperative ergonomics, reduce operator distance from radiation and shorten the learning curve. In this study we aimed to assess the clinical performance and feasibility of the ILY robot during retrograde intrarenal surgery (RIRS) and combined endoscopic procedures (miniECIRS). Material and methods: The RIRS procedures were performed using the ILY robotic arm in 57 adult patients (46 RIRS and 11 miniECIRS) from 2022 to 2023. All procedures were performed in the supine position. Pre-stenting was not the standard of care. Results: Turning on and calibration of the device took approximately 100 s. Average draping time was 93 s using original ILY drapes and 47 s using classic drapes designed for C-arm covering. Mean docking time was 73 s in procedures with ureteral access sheath (UAS) and 61 s in procedures without it. The undocking took less than 60 s in every case. Average procedure time was 63 min for RIRS and 55 min for miniECIRS. Endoscopically proven stone-free rate was achieved in 37 (80.4%) RIRS and 10 (90.9%) miniECIRS patients. A total of 17 (36.9%) RIRS and 8 (72.7%) miniECIRS procedures required conversion in order to perform basketing and stone fragments retrieval/transposition. Conclusions: The use of ILY robot during endourological procedures is feasible and urologists that are familiar with the device controller do not require extensive training. The time needed for device draping, docking and undocking was approximately 4 minutes. Moreover, use of the robot resulted in satisfactory stone-free rates.

Left endoscopic combined intrarenal surgery with electrocoagulation hemostasis and right flexible ureteroscopic lithotripsy for bilateral upper urinary tract stones: a case report.

Background: Percutaneous nephrolithotomy (PCNL) is the first-line treatment for large renal stones. However, multi-tract or staged procedures may be necessitated in bilateral or anatomically-complex stones to achieve stone clearance. Endoscopic combined intrarenal surgery (ECIRS) integrates the advantages of PCNL and retrograde intrarenal surgery. In this article, we detail a hybrid surgical technique adopted for the management of complex simultaneous bilateral upper urinary tract stones. In addition, we discuss the advantages and disadvantages of combining a variety of new techniques that may improve post-operative outcomes and patient satisfaction. Case Description: We report the case of a 36-year-old male with a large left renal pelvis stone, right proximal ureteric stone, and bilateral renal stones. Biochemical results showed raised inflammatory markers but he denied pre-stenting and staged surgery. After receiving 3-day antibiotic prophylaxis, he underwent an elective hybrid procedure. Under split-leg prone position, we performed a hybrid procedure that included left ECIRS with tubeless single-tract mini PCNL and left flexible ureteroscopy, and right flexible ureteroscopic lithotripsy. Hemostasis was achieved by electrocauterization with a novel device. The patient made an uneventful recovery. Follow-up computed tomography (CT) at 1-month revealed complete stone clearance. Conclusions: Unilateral ECIRS with tubeless single-tract mini PCNL with electrocoagulation hemostasis and adjacent retrograde intrarenal surgery in split-leg prone position is a safe, feasible, and efficient technique to manage large renal stones.

Simultaneously combining a thulium fiber laser and holmium:YAG laser in vacuum-assisted mini-endoscopic combined intrarenal surgery on a complex renal calculus: A case report.

Employing percutaneous nephrolithotomy to manage a complex renal calculus has always been challenging due to the blood transfusion requirement and the frequent necessity of using multiple access tracts. We report a novel treatment modality in the case of a 65-year-old male with a complex, large-volume renal calculus who was successfully treated by vacuum-assisted miniaturized endoscopic combined intrarenal surgery using the combination of a thulium fiber laser in retrograde fashion with a holmium:YAG laser in antegrade fashion. The kidney stone was entirely cleared, and the patient fully recovered with no adverse event.

Nonpapillary Prone Endoscopic Combined Intrarenal Surgery (ECIRS): Five-Year Experience and Outcomes from a High-Volume Center.

Endoscopic combined intrarenal surgery (ECIRS) provides simultaneous retrograde and percutaneous access to the upper urinary tract. The purpose of this study is to present revised data, tips and tricks, and technique modifications arising from our five-year experience with ECIRS. The data of 62 patients who underwent nonpapillary prone ECIRS from January 2019 to November 2023 were prospectively collected. All cases were performed in the prone position. Inclusion criteria were complex stone cases with stones in multiple calyces requiring either multiple accesses or multiple sessions to achieve stone-free status. Patients' mean age was 54.4 ± 12.39 years, while the mean stone size was 39.03 ± 13.93 mm. The mean operative time was 51.23 ± 17.75 min. Primary and final stone-free rates were 83.8% and 90.3%, respectively. In total, nine patients presented with postoperative complications, which were all Grade II ones. The holmium-YAG laser type during retrograde lithotripsy was associated with significantly shorter operative times compared to the thulium fiber laser. Nonpapillary prone ECIRS is a feasible, safe, and efficient approach for patients with specific stone and anatomy characteristics. The implementation of more, higher-evidence studies is of utmost importance so that safer conclusions can be drawn.

2022 Recommendations of the AFU Lithiasis Committee: Combined approach for the management of kidney and ureteral stones (Endoscopic Combined IntraRenal Surgery, ECIRS).

The primary objective of the combined approach is to limit the number of percutaneous access tracts for the treatment of staghorn, or complex kidney stones by simultaneous percutaneous antegrade and retrograde ureteroscopy. The other indication is the simultaneous presence of several kidney and ureteral stones or of an impacted pelvic stone. The combination of the two techniques may increase the stone-free rate and decrease the retreatment rate of complex stones compared with percutaneous nephrolithotomy alone. The patient is usually in the modified supine position. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendation (CPR) method and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU Guidelines on urolithiasis. 2022] and their adaptability to the French context.

Ambulatory Minimally Invasive Endoscopic Combined Intrarenal Surgery in Management of Large Impacted Proximal Ureteral Calculi: A Feasibility Study at a Tertiary Referral Center.

Aim: To conduct a comparative, nonrandomized study to assess the feasibility of mini-Endoscopic Combined Intrarenal Surgery (ECIRS) using supine Mini-percutaneous nephrolithotomy (PCNL) access (16F) in Galdakao-Modified Supine Valdivia position for managing proximal large-volume impacted ureteral calculi as ambulatory day-care surgery vis-a-vis standalone ureteroscopy (URS) with push-back PCNL, if needed. The primary aim was to study the outcomes and stone-free rates (SFRs). Secondary aim was to compare the intraoperative and short-term postoperative complications. Materials and Methods: Data of 60 patients undergoing ECIRS (Group 1) from January 2016 to December 2019 were collected prospectively in a nonrandomized fashion from a single center after Ethics Committee approval. A matched-paired analysis was performed with retrospectively collated data of 60 patients undergoing standard URS/pushback PCNL (Group 2) using analysis of variance, Fisher's exact test, and Chi-square test. p < 0.05 was considered statistically significant. Outcomes and Results: Group 1 patients had a significantly shorter procedure time vs Group 2 (42.1 ± 11.2 minutes vs 52.1 ± 13.7 minutes; p < 0.001). Group 1 (59/60) patients had an overall single stage SFR of 98.3%, which was significantly higher than single-stage SFR of 83% in Group 2 (50/60) (p < 0.002). Group 2 patients had a higher incidence of fever (10 vs 4, p = 0.01). However, there were no cases of sepsis in either group. Rest of the complications were comparable for both, as the need for ancillary procedures was significantly higher in Group 2 (10% vs 1.7%, p < 0.001). Patients were discharged on the same day in both groups. Conclusions: The findings of our study suggest that, in large and impacted proximal ureteric stones, combined minimally invasive endoscopic approach offers the best option to render the patient stone free by a single intervention. With better intra- and postoperative outcomes and safety profile, Mini-ECIRS may be considered as an ambulatory procedure in this setting.

A giant ureteric calculus successfully removed by mini-endoscopic combined intrarenal surgery: A case report.

Giant ureteric calculi are extreme rare and associated with a subsequent decline in the function of the affected kidney. We report the case of a 58-year-old male with a huge opaque ureteral calculus found during a routine medical check-up. Computed tomography revealed an 11 × 12 × 67 mm3 ureteral stone at the right proximal ureter with mild hydronephrosis. The patient was treated successfully by mini-endoscopic combined intrarenal surgery, and the entire stone was retrieved. The patient recovered fully without additional complications.

Nonpapillary prone endoscopic combined intrarenal surgery: effectiveness, safety and tips, and tricks.

PURPOSE: To evaluate the effectiveness and safety of nonpapillary prone endoscopic combined intrarenal surgery (ECIRS) and provide practical tips and tricks for the successful accomplishment of the procedure respecting the anatomical particularities. MATERIAL AND METHODS: This study is an analysis of a prospectively collected database including all cases of ECIRS performed between January 2019 and December 2021 in a high-volume tertiary center. All patients underwent the procedure in prone-split leg position. A nonpapillary renal puncture was performed. The used access sheaths were 22Fr or 30Fr. Lithotripsy was performed anterogradely with a dual-energy lithotripter with incorporated suction and retrogradely with holmium Yttrium-Aluminum-Garnet laser. RESULTS: A total of 33 patients were included. The initial stone-free rate (SFR) was 84.8% and the final SFR was 90.9%. The median stone size was 35 mm and 60% of patients had staghorn calculi. The prevalence of renal abnormalities was 21.3%, including 3 cases of horseshoe kidney, 2 cases of malrotation and 2 cases with complete duplicated systems. The median operative time was 47 min. The median hospital stay was 3 days and median hemoglobin loss was 1.2 gr/dL. Overall, the complication rate was 9.1%, all being Grade II complications (n = 2 fever and n = 1 transient bleeding). CONCLUSIONS: Nonpapillary prone ECIRS is an effective and safe procedure. Standardization of the procedure is critical to achieve good outcomes. Patients who benefit the most are probably the ones where additional punctures can be avoided using this technique, namely patients with renal abnormalities, incrusted ureteral stents and staghorn stones.

Supine Percutaneous Nephrolithotomy.

Percutaneous nephrolithotomy (PCNL) has evolved many a fold and was originally described in supine position by Valdivia et al. In this position, the direction of the tract is posterior and thus preserves a low pressure in the renal pelvis, and thereby reduces the risk of fluid absorption and allows spontaneous clearance/washout of fragments by gravity-directed flow of fluid. Supine PCNL is feasible in most situations. It is an important tool for patients who have musculoskeletal abnormalities precluding prone positioning. It gives the surgeon a simultaneous opportunity to do flexible ureteroscopy. Mobility of the kidney may make the puncture difficult. Suctioning of the dust using the suction sheath in supine PCNL makes the procedure more effective.

Robot-Assisted Mini-Endoscopic Combined Intrarenal Surgery for Complex and Multiple Calculi: What Are the Real Advantages?

Background: To determine the stone-free rates (SFR) with robot-assisted mini-endoscopic combined intrarenal surgery (mini-ECIRS) and evaluate the impact of intraoperative assessment of stone-free status compared to postoperative non-contrast computed tomography (NCCT) scan findings. Methods: A total of 42 consecutive patients (44 renal units) diagnosed with complex/multiple renal stones were enrolled and reviewed in a retrospective manner. While retrograde access with the flexible scope was performed by using Avicenna Roboflex, mini-percutaneous nephrolithotomy was performed through a 16.5F sheath. Demographic, clinical characteristics of the cases along with perioperative complications were recorded, analyzed, and compared to the reported data in the literature. Results: Forty-two renal units (95.5%) were endoscopically confirmed to be stone-free at the end of the procedure, of which all were confirmed to be stone-free in postoperative NCCT examination. Complications were observed in 3 of the 42 (7.1%) patients, which were classified as Clavien grade I. The mean operation and fluoroscopy time were 103.7 ± 20.6 minutes and 71 ± 13.7 seconds, respectively. Conclusion: Our results demonstrate that robot-assisted mini-ECIRS could reveal high SFR in complex and multiple stones. In addition, endoscopic flexible ureteroscopic evaluation of the collecting system at the end of the procedure could let the surgeon predict stone-free status more reliably and successfully.

Endoscopic Combined Intrarenal Surgery vs Percutaneous Nephrolithotomy for Large and Complex Renal Stone: A Systematic Review and Meta-Analysis.

Background: Managing complex and large renal stones with percutaneous nephrolithotomy (PCNL) is difficult because of the likelihood of residual stones and multiple access. Endoscopic combined intrarenal surgery (ECIRS) is introduced as an improvement to the procedure to manage stones in one session. The objective of this systematic review and meta-analysis is to compare the efficacy and safety between ECIRS and PCNL for treating large and complex renal stones. Materials and Methods: We conducted a systematic review in the Embase, Scopus, and MEDLINE databases based on the 2020 Preferred Reporting Items for Systematic Review and Meta-Analyses guideline. Eligible studies comprised both randomized and nonrandomized studies comparing ECIRS and PCNL. Results: A total of five nonrandomized studies and one randomized controlled trial were included. The analysis was divided into two subgroups based on the PCNL type, a conventional PCNL (cPCNL) and a mini-PCNL (mPCNL). The one-step stone-free rate (SFR) of ECIRS were significantly higher compared with both the cPCNL (odds ratio [OR] 5.14, 95% confidence interval [CI] 2.54 to 10.4, p < 0.001) and mPCNL (OR 4.27, 95% CI 2.57-7.1, p < 0.001). There were no significant differences in mean operative time and hemoglobin drop between both groups (p > 0.05). The use of auxiliary procedures was significantly higher in both PCNL groups compared with the ECIRS group (OR 0.19, 95% CI 0.13-0.30, p < 0.001). The overall complication rate of ECIRS was lower compared with PCNL (OR 0.43, 95% CI 0.21-0.85, p = 0.02), especially urosepsis, in which the incidence was lower compared with cPCNL (OR 0.14, 95% CI 0.02-0.78, p = 0.02), but not mPCNL (p > 0.05). Conclusion: ECIRS is an effective and safe treatment particularly for large and complex nephrolithiasis, with significantly higher one-step SFR, a lower necessity for auxiliary procedures, and a lower complication rate compared with PCNL.

Laparoscopic assisted mini-ECIRS for ectopic kidney lithiasis: A case report and literature review.

INTRODUCTION: Ectopic kidney is a rare anatomic variant with an incidence of about 1 in 900. Renal stones can pose a challenge when a standard approach is not possible. Laparoscopic-assisted endourologic procedure can be a feasible and safe choice. CASE REPORT AND LITERATURE REVIEW: We present a case of 32 years old man with spastic quadriplegia, megacolon and pelvic kidney undergoing intervention of laparoscopic-assisted Mini ECIRS for staghorn stone of the left pelvic kidney. To the best of our knowledge, only 59 cases are reported in the literature concerning laparoscopically assisted encdourologic treatment which seems a feasible, safe and adaptable technique in selected complex cases. CONCLUSION: Laparoscopic-assisted mini ECIRS is a viable option for the treatment of ectopic kidney stones. This technique should be considered when anatomical anomalies are encountered, to avoid puncture-related complications.

Tips and Tricks to Improve Ergonomics, Efficacy, Versatility, and Overcome Limitations of Micro Percutaneous Nephrolithotomy.

Percutaneous Nephrolithotomy (PCNL) has evolved over the decades from Standard to Mini to Ultramini PCNL to Micro-perc, with miniaturisation being the dominant theme and supine approach gaining momentum world over. Aim: In literature, miniaturised PCNL with microperc needle access system has raised concerns of intrarenal pressure and has some limitations with its success for larger stones. Our tips and tricks explain how to overcome these pitfalls by utilising the full construct of the needle system to its maximum potential. These will in turn help make the procedure versatile, precise, ergonomical, and enhance a surgeon's experience with improved outcomes for patients especially in large renal stones. Materials and Methods: We describe the limitations of microperc needle access as stated in literature and proposals by the co-authors using microperc for miniaturised access on how to overcome the same. Results: A simplified table describing the limitations and tips and tricks on overcoming these is provided for quick reference. Conclusion: As Technological advancements and techniques for miniaturised access in urolithiasis improve, we believe our suggestions will help surgeons overcome the quoted limitations of microperc needle access for miniaturised PCNL, making this a versatile, safe and efficacious technique even in large and complex stones. A multi centre trial will be the best way to validate the suggestions proposed in this article.

X-Ray-Free Endoscopic Combined Intrarenal Surgery for Complex Proximal Ureteral Stone: A Case Report.

X-ray-free endoscopic combined intra renal surgery (ECIRS) is a feasible alternative to avoid radiation exposure to both surgical teams and patients, but has not been reported prior. The aim of this report is to present our first-hand experience of performing X-ray-free ECIRS for complex ureteral stone. A 57-year-old female presented with right flank pain, fever, dysuria, and leukocytosis. The computed tomography scan showed right impacted proximal ureteral stone sized 33 ´17 mm and grade IV hydronephrosis. Percutaneous nephrostomy was performed immediately. With improvement of clinical symptoms two days after nephrostomy, X-ray-free ECIRS was performed. The patient was placed in a Galdakao-modified supine position. During ureteroscopy (URS), there was noted right ureteral stenosis in the distal part of the stone, which could be passed. However, the stone was impacted and the semi-rigid URS was not able to push it. Therefore, antegrade approach with percutaneous nephrolithotomy was performed. Previous nephrostomy tract was used as percutaneous access. Tract dilatation was performed under direct visualization from the URS. The 28 Fr rigid nephroscope was used during the ECIRS procedure. The stone was fragmented using shock-pulse lithotripters. There was no residual stone or infundibular laceration after the procedure. A 6 Fr double J stent was inserted retrogradely due to ureteral stenosis. There was no complication during and after the procedure. The patient was discharged on post-operative day three. X-ray free ECIRS for complex proximal ureteral stone was possible and showed good results.

A novel approach in creating nephrostomy using a double-lumen access sheath during endoscopic combined intrarenal surgery.

BACKGROUND: This study aimed to evaluate the safety and efficacy of an inner ureteral access sheath (i-UAS) with a double-lumen channel used in ureteroscopic lithotripsy (URS) as a dilator for the percutaneous tract in endoscopic combined intrarenal surgery (ECIRS). METHODS: This was a single-center cohort study conducted from January 2016 to April 2020. We used an i-UAS as a dilator and a double-lumen catheter to insert a safety guidewire during the creation of the nephrostomy tract in ECIRS. Univariate and multivariate analyses were performed to assess the association between the perioperative parameters and the use of i-UAS. The primary endpoint was perioperative complications, and secondary endpoints were stone-free rate (SFR), operative time, fluoroscopy time, and duration of hospitalization. RESULTS: In total, 221 patients were enrolled during the study period. Patients were divided into an i-UAS dilation group (n=108) and a one-shot dilation group (n=113). No differences were observed between the two groups in terms of patient history. Univariate analyses indicated that, in the i-UAS dilation group, the operative time was shorter [105.50 (83.75-143.25) vs. 121.00 (90.00-155.00) min; P=0.02] and the modified Valdivia position was more frequently selected. Multivariate analyses showed no significant differences in the frequency of complications, such as urinary injury or postoperative pyelonephritis, but it showed a significantly shorter operative time as well as fewer tract creation troubles in the i-UAS dilation group. CONCLUSIONS: Using an i-UAS as a dilator and a double-lumen catheter to insert a safety guidewire during ECIRS is a convenient and safe technical method for creating a nephrostomy tract that can reduce the operative time.