Efficacy and Safety of Flexible and Navigable Suction Ureteral Access Sheath Versus Conventional Ureteral Access Sheath in Retrograde Intrarenal Surgery: An Updated Systematic Review and Meta-Analysis

<i>Background and Objectives</i>: Ureteral access sheaths (UASs) are widely used in retrograde intrarenal surgery (RIRS) to facilitate irrigation and instrument access. Recently, flexible and navigable suction UASs (FANS-UASs) have been developed to enhance visibility and stone fragment evacuation; however, their comparative effectiveness remains uncertain. This study aimed to evaluate the clinical outcomes of FANS-UAS versus conventional UAS during RIRS for renal stones. <i>Materials and Methods</i>: A systematic review and meta-analysis were performed following PRISMA guidelines. PubMed, Embase, and the Cochrane Library were searched through May 2025 for comparative studies of FANS-UAS and conventional UAS. Study quality was assessed using the Scottish Intercollegiate Guidelines Network checklist. Primary outcomes included stone-free rate (SFR), operative time, complications, and hospital stay. Subgroup analyses were conducted according to stone size (≤2 cm vs. >2 cm). <i>Results</i>: Nine studies involving 1791 patients were included. FANS-UAS demonstrated a significantly higher SFR (OR = 5.99, 95% CI: 2.86-12.51; I² = 86.7%) and fewer complications (OR = 0.33, 95% CI: 0.23-0.45; I² = 0%). Operative time and hospital stay did not differ significantly between groups. Subgroup analysis showed no significant SFR difference for stones ≤2 cm, whereas for stones >2 cm, FANS-UAS tended to yield higher SFR-though based on limited evidence. <i>Conclusions</i>: FANS-UASs appear to improve stone clearance and reduce perioperative complications in RIRS without increasing operative burden. While further high-quality randomized trials are needed, current evidence supports the growing adoption of FANS-UAS in endourological practice.