RIRS with flexible vacuum-assisted ureteral access sheath for large renal stones: a prospective randomized controlled study

To observe the efficacy and safety of retrograde intrarenal surgery (RIRS) combined with a flexible vacuum-assisted ureteral access sheath (FV-UAS) in patients with large renal stones (LRS). A total of 149 patients with LRS were prospectively randomized into two groups: 75 in the FV-UAS group and 74 in the minimally invasive percutaneous nephrolithotomy (MPCNL) group. The primary outcome was the stone-free rates (SFRs) on the first postoperative day. Secondary endpoints included the total SFRs 1 month postoperatively, lithotripsy time, hemoglobin reduction, length of postoperative hospital stay, quality of life (QoL) score improvement, incidence of ureteral stricture at 3 months postoperatively, and any surgery-related complications. Patient demographics and preoperative clinical characteristics showed no apparent difference between the two groups (all P > 0.05). Postoperative data revealed a significantly longer lithotripsy time in the FV-UAS group than the MPCNL group (113.1 vs. 82.5 min, P < 0.001). The mean decrease in hemoglobin was significantly lower in the FV-UAS group than in the MPCNL group (8.2 vs. 17.7 g/L, P < 0.001). Similarly, the average hospital stay was shorter in the FV-UAS group than the MPCNL group (1.7 vs. 5.1 d, P < 0.001). Meanwhile, SFRs on the first postoperative day and 1 month postoperatively were statistically similar between the two groups (P > 0.05). QoL improvement was significantly higher in the FV-UAS group than in the MPCNL group (33.4 vs. 26.9, P < 0.001). The difference in ureteral stricture at 3 months postoperatively was not statistically significant (P > 0.05). Notably, the overall rate of postoperative complications was markedly lower in the FV-UAS group than in the MPCNL group (P < 0.05). Our study showed the safety and feasibility of applying RIRS combined with FV-UAS for LRS treatment, providing advantages such as high SFRs, minimal trauma, fast recovery, and low incidence of postoperative complications. It can be used as a clinical treatment alternative for LRS. The protocol for this study has been accepted by the Chinese Clinical Trial Registry (Ethics approval number: ChiCTR2200056402; Date of registration: 02-05-2022).