Retrograde intrarenal surgery combined with flexible vacuum-assisted ureteral access sheath versus traditional ureteral access sheath for 1-2 cm lower calyceal renal stones: a prospective, randomized controlled study

Objective: To evaluate the efficacy and safety of retrograde intrarenal surgery (RIRS) combined with a flexible vacuum-assisted ureteral access sheath (FV-UAS) in patients with 1-2 cm lower calyceal renal stones.Patients and methods: In total, 203 patients with calyceal stones were prospectively randomized into two groups (Clinical trial registration number: ChiCTR2200056402).Of them, 101 patients were assigned to the FV-UAS group and 102 to the traditional UAS group (control).The primary outcome was the stone-free rate (SFR) on postoperative day 1 and in the 4th week.Secondary outcomes included operative time, length of postoperative hospital stay, hospitalization costs, and procedure-related complications.Results: No significant differences were noted in baseline demographics and preoperative clinical characteristics between the two groups (all P > 0.05).Postoperative data indicated that the SFRs on both postoperative day 1 and week 4 were significantly higher in the FV-UAS group than in the traditional UAS group (86.1% vs. 70.6%,P = 0.007; 92.1% vs. 82.4%,P = 0.038, respectively).Hospitalization costs were also lower in the FV-UAS group than in the traditional UAS group ($2524.1 vs. $2635.4,P < 0.001).Furthermore, the incidence rates of postoperative fever, perirenal hematoma, and urosepsis were significantly lower in the FV-UAS group than in the traditional UAS group (fever: 2.0% vs. 8.8%, P = 0.031; hematoma: 0.0% vs. 4.9%, P = 0.024; urosepsis: 1.0% vs. 7.8%, P = 0.018).Conclusions: Our findings suggest that the combination of FV-UAS and RIRS offers a promising treatment approach for 1-2 cm lower calyceal renal stones.This method results in higher SFRs, lower complication rates, and reduced hospitalization costs, making it a valuable technique for clinical adoption.