Comparing Thulium Fiber Laser vs Holmium:Yttrium-Aluminum-Garnet Laser for Ureteric Stone Lithotripsy: A Prospective, Randomized Controlled Trial

Introduction: Holmium:yttrium-aluminum-garnet (Ho:YAG) laser is the gold standard for ureteroscopic lithotripsy, but faces challenges such as stone retropulsion. The emerging thulium fiber laser (TFL) offers advantages, including higher efficiency, smaller fiber size, and reduced retropulsion. Our study aims to compare the stone ablation efficiency of TFL and Ho:YAG laser. Method: This study is a prospective, single-center, randomized controlled trial comparing TFL and Ho:YAG laser for ureteral stone lithotripsy in 35 patients. The primary outcome is stone ablation efficiency, with secondary outcomes including total operation time and laser time, the degree of retropulsion, clarity of endoscopic view, hospital stay, 30-day complications, 3-month stone-free rate, and requirement for auxiliary procedure. The stone-free rate is defined as the absence of detectable stones on a post-operative noncontrast CT scan conducted 3 months after the procedure. Result: Sixteen patients and 19 patients were randomized in the Ho:YAG group and TFL group, respectively. Patient demographics were comparable except for more men in the TFL group (81.3% vs 68.4%). The stone ablation rate (the volume of stone ablated per minute of laser time) was comparable between both groups (1.12 mm³/s for the TFL group and 1.33 mm³/s for the Ho:YAG group, p = 0.772). TFL had shorter laser time (3.02 vs 5.78 minutes, p = 0.013), less retropulsion ( p = 0.048), and a higher stone-free rate (100% vs 78.9%, p = 0.0015). Conclusions: Lithotripsy using a thulium fiber laser achieves a stone ablation rate comparable to that of the holmium:YAG laser. The thulium fiber laser results in a higher stone-free rate while keeping complication rates similar.