Outcomes and safety of ureterorenoscopy with pulsed thulium:YAG laser for urolithiasis: the largest prospective single-center series

BACKGROUND: Laser lithotripsy is central to the endoscopic management of renal and ureteral stones. Thulium:YAG (Tm:YAG) laser has emerged as a promising platform, although clinical evidence on its safety, effectiveness, and real-world performance remains limited. The aim of this article is to evaluate the clinical performance, effectiveness, and safety of Tm:YAG laser lithotripsy in patients undergoing URS/ULT or RIRS at a high-volume center. METHODS: Patients undergoing URS/ULT or RIRS for urolithiasis with the Tm:YAG laser were prospectively enrolled at a single high-volume institution between December 2023 and February 2026. Demographic, clinical, radiological, intraoperative, and postoperative variables were collected. Continuous variables were reported as mean and standard deviation or median with interquartile range, as appropriate. Mann-Whitney U Tests assessed associations between perioperative variables and postoperative outcomes in the overall cohort and separately in renal and ureteral stone cohorts. Stone-free rate (SFR) and clinically significant stone-free rate (CSSFR; residual fragments ≤3 mm) were evaluated on 4-week follow-up imaging. Complications were classified according to the Clavien-Dindo system. RESULTS: (IQR 203-2142), and median stone density was 1183 HU (IQR 867-1445). Mean operative time was 65.3±43.2 minutes, median laser activation time was 21.1 minutes (IQR 13.6-36.8), and median total laser energy was 8.2 kJ (IQR 2.4-23.1). At 4 weeks, overall SFR was 85.6%, including 80.5% in the renal cohort and 92.1% in the ureteral cohort; CSSFR was 89.8%. Postoperative complications occurred in 27 patients (6.3%), with no Clavien-Dindo grade ≥III events. Failure to achieve SFR or CSSFR was associated with greater stone burden, higher stone density, longer operative and laser activation times, higher total laser energy, and lower ablation speed. CONCLUSIONS: In this prospective high-volume single-center cohort, Tm:YAG laser lithotripsy demonstrated favorable efficacy and safety for renal and ureteral stones, supporting its feasibility for URS/ULT and RIRS. Comparative studies are needed to define its role among established laser technologies.