Thulium Fiber Laser Versus Low-power Holmium YAG Lithotripsy during Flexible Ureteroscopy: A Randomized Controlled Trial

Purpose To evaluate the effectiveness and safety of thulium fiber laser (TFL) compared to low-power holmium:YAG (Ho:YAG) laser lithotripsy in flexible ureteroscopy for kidney and proximal ureteral stones of 10–20 mm. Methods This prospective, single-center randomized controlled trial enrolled 231 patients with renal and/or proximal ureteral stones (10–20 mm) at Hazm Mebaireek General Hospital, Qatar (January 2022-December 2024). Patients were randomized 1:1 to TFL (n = 121; 8W, 20Hz, 0.4J) or Ho:YAG (n = 110; 8W, 10Hz, 0.8J) lithotripsy using dusting technique. Outcome assessors were blinded. Primary outcomes were stone-free rate (SFR) at 4–6 weeks and dusting efficiency. Secondary outcomes included operative time, complications, and retreatment rates. Results Baseline characteristics were comparable (mean age 39.4 ± 9.2 years; median stone volume 1175 mm³). Complete stone clearance was similar (TFL 50.5% vs Ho:YAG 50.0%, p = 0.949). However, total SFR including fragments ≤4mm was significantly higher with TFL (94.4% vs 86.0%, p = 0.048; NNT = 12). Dusting efficiency was comparable (1.78 vs 1.82 sec/mm³, p = 0.571), as was median lasering time (40 minutes, p = 0.723). Complication rates were low and similar between groups (TFL 6.6% vs Ho:YAG 4.6%, p = 0.496) with no ureteral injuries. Retreatment rates were comparable (17.4% vs 20.0%, p = 0.606). Conclusions TFL demonstrated superior stone-free rates compared to low-power Ho:YAG laser (94.4% vs 86.0%) for stones 10-20mm, with comparable safety, dusting efficiency, and operative times, representing an effective alternative to conventional Ho:YAG lithotripsy.