A Comparative Study of Flexible Navigable Vacuum-Assisted Ureteral Access Sheath and Traditional Ureteral Access Sheath in Retrograde Intrarenal Surgery: Evaluating the Impact of Hydronephrosis on Stone-Free Rate and Complications

<b><i>Background:</i></b> Retrograde intrarenal surgery (RIRS) is a widely used minimally invasive technique for renal stone management. Recently, flexible navigable vacuum-assisted ureteral access sheaths (FV-UASs) have been introduced to enhance RIRS outcomes. This study aimed to evaluate the efficacy of FV-UAS compared with traditional UAS (T-UAS) in RIRS, with a specific focus on the impact of hydronephrosis. <b><i>Methods:</i></b> A retrospective multicenter study was conducted involving 207 patients undergoing RIRS for renal stones. Patients were divided into two groups based on the type of UAS used: FV-UAS (<i>n</i> = 105) or T-UAS (<i>n</i> = 102). Demographic data, stone characteristics, operative time, complications, and stone-free rates (SFRs) were analyzed. The degree of hydronephrosis was assessed using the Society of Fetal Urology grading system. <b><i>Results:</i></b> The FV-UAS group demonstrated significantly shorter operative times (median: 50 minutes <i>vs</i> 57.5 minutes, <i>p</i> = 0.039) and a higher SFR at 1-week postoperatively (47.6% <i>vs</i> 23.5%, <i>p</i> < 0.001) compared with the T-UAS group. However, there was no significant difference in SFR at 1 month (75.2% <i>vs</i> 68.6%, <i>p</i> = 0.290). Postoperative fever was significantly lower in the FV-UAS group (3.8% <i>vs</i> 18.6%, <i>p</i> = 0.001). Importantly, the degree of hydronephrosis did not significantly impact the outcomes that performed RIRS with FV-UAS. <b><i>Conclusion:</i></b> FV-UAS offers potential advantages over T-UAS in RIRS, including shorter operative times, improved early stone-free status, and reduced postoperative complications. Hydronephrosis did not appear to affect the efficacy of FV-UAS. These findings suggest that FV-UAS may be a valuable tool in optimizing RIRS outcomes.