Comparison of Flexible and Navigable Suction Versus Conventional Ureteral Sheath in Retrograde Intrarenal Surgery: A Randomized Controlled Prospective RIRSearch Group Study

Objective: To compare the efficacy and safety of the flexible and navigable suction ureteral access sheath (FANS-UAS) against the conventional ureteral access sheath (CUAS) in retrograde intrarenal surgery (RIRS). Materials and Methods: A total of 161 patients who underwent RIRS at seven centers using similar surgical methods (thulium fiber laser and 7.5 F disposable flexible ureterorenoscope) were prospectively enrolled in the study between May 2024 and September 2025. The patients were randomized into two groups based on the use of UAS (Group 1: CUAS; Group 2: FANS-UAS). Demographic and clinical data of the patients, stone characteristics, surgical data, perioperative and postoperative complications, duration of hospitalization, and stone-free rates (SFRs) were analyzed for comparison. Results: Of the 161 patients included in the study, 79 received a CUAS and 82 received a FANS-UAS. The groups were demographically similar ( p > 0.05). The postoperative SFR at 1 month was statistically significantly higher in the FANS-UAS group (79.3% vs 63.3%, p = 0.041), and the operative time was shorter in the CUAS group ( p = 0.011). The perioperative bleeding rate was higher in the FANS-UAS group ( p = 0.034), although there was no significant difference in postoperative hemoglobin decrease. No significant difference was observed between the two groups in terms of postoperative complications ( p = 0.162). Conclusion: The FANS-UAS is an effective method that increases SFR compared to the CUAS. Although the FANS-UAS prolongs operation time and increases perioperative bleeding, both FANS-UAS and the CUAS are similarly safe in terms of postoperative complications.