Clinical efficacy and safety of flexible ureteroscopic lithotripsy using 365 μm holmium laser for nephrolithiasis: a prospective, randomized, controlled trial

Purpose To compare the clinical efficacy and safety between the FURL with 365 μm and 200 μm holmium laser for treating nephrolithiasis. Materials and methods A prospective randomized controlled trial was performed including analysis of data from 200 patients with nephrolithiasis. A total of 180 patients were randomized into two groups according to 1:1 ratio. In the 365 μm holmium laser group, kidney stones were disintegrated into less than 2 mm fragments with a 365 µm holmium laser fiber with the settings of 30–45 W under direct visualization; in the control group, the conventional 200 μm holmium laser was used. Descriptive statistics and logistic regression analyses tested the association among operation time, stone-free rate (SFR) and incidence of complications. Results Operation time in the FURL with 365 μm laser was significantly shortened and no significance was observed in the complication rate. Stone size and location were identified as two major confounding factors for the operation time and SFR. Moreover, the FURL using 365 μm laser showed less operation time for renal stones with the diameter between 1 and 2 cm, stones located in lower calyx and multiple calculi; stones larger than 2 cm and/or located in lower pole inclined to present better SFR using the FURL with 365 μm laser. Conclusions The FURL combined with 365 μm holmium laser is safer and highly efficacious for the management of nephrolithiasis when compared to conventional FURL procedures, especially for those located in lower pole and larger than 2 cm.