Efficacy of flexible ureterorenoscopy in treating multiple renal stones: a cohort study.

Introduction: While the efficacy of flexible ureterorenoscopy (URS) in managing solitary kidney stones (KSs) is widely acknowledged, its effectiveness in treating multiple stones has scarcely been investigated. This study aims to assess the effectiveness and safety of retrograde intrarenal surgery (RIRS) utilizing flexible URS and laser lithotripsy in the management of multiple KSs.  Methods: This study was a single-group cohort study conducted on patients with multiple KSs who underwent treatment with RIRS using flexible URS and laser lithotripsy. Stone-free status was considered as the lack of residual stone fragments or any residual stone of any size. The first follow-up appointment was arranged 3-4 weeks following the procedure. If significant residual stones were present, patients underwent reintervention within 2-4 weeks.

Results: A total of 110 patients with multiple KSs were included. The mean stone burden was 27.5 ± 7.9 mm, and the mean duration of the operation was 54.9 ± 19.7 minutes. Seven cases (6.3%) experienced intraoperative complications, while postoperative complications were found in eight cases (7.3%). After four weeks, a stone-free rate (SFR) was documented in 80.9% of the cases, and this rate increased to 93.6% after three months. The SFR after three months was significant with Guy's stone score (p < 0.001); however, it did not reach a significant level with any other parameters.  Conclusions: The RIRS with flexible URS may be an effective and potentially safe procedure for treating multiple KSs. It may yield a favorable SFR with an acceptable complication rate.