This study aimed to assess and compare the efficacy and safety of various ratio of endoscope-sheath diameter (RESD) for the suction ureteral access sheath (S-UAS) used in retrograde intrarenal surgery (RIRS) to treat renal and ureteral stones.

We conducted a single-center, retrospective cohort study of patients who underwent RIRS between March 2024 and March 2025. Participants were divided into two groups based on the RESD of the suction ureteral access sheath (S-UAS): ≤0.75 and >0.75. We recorded patient baseline characteristics, immediate and 1-month postoperative stone-free rates (SFR), operative times, complication rates, and the need for auxiliary procedures. Patients were further stratified by stone size (≤15 mm vs. >15 mm), stone location, and whether they had a single or multiple stones. Statistical analyses were conducted to compare outcomes between the two groups.

A total of 50 patients were included in the study, evenly divided into two groups based on RESD values: 25 patients in the S-UAS group with RESD ≤ 0.75, and 25 patients with RESD > 0.75. The stone-free rate (SFR) postoperatively showed no significant difference between the two groups (56.0% vs. 60.0%, p = 0.774). Operative times were comparable (110.84 ± 57.5 vs. 102.96 ± 53.9 minutes, p = 0.62). Although not statistically significant, a trend toward lower postoperative serum white blood cell (WBC) counts was observed in the RESD ≤ 0.75 group (10.12 ± 3.31 vs. 12.40 ± 5.27, p = 0.073). Subgroup analysis revealed a statistically significant lower postoperative WBC count in patients with multiple stones within the RESD ≤ 0.75 group (9.99 ± 3.45 vs. 12.79 ± 3.68, p = 0.031).

Postoperative SFR may not significantly differ between varying RESD groups when using S-UAS in RIRS. However, the use of S-UAS with RESD ≤ 0.75 is associated with lower postoperative serum WBC levels compared to RESD > 0.75. Further studies with larger cohorts and extended follow-up periods are necessary to confirm and expand upon these findings.