ObjectiveTo evaluate the safety and efficacy of flexible ureteroscopic lithotripsy for patients with renal calculi of more than 2 cm in diameter. MethodsThe Clinical data of 37 patients with renal calculi of more than 2 cm in diameter treated with holmium laser lithotripsy through flexible ureteroscope between December 2012 and March 2015 were retrospectively analyzed. In this group, stone diameter was between 2.0 cm and 3.5 cm, including 22 cases of single stone and 15 cases of multiple stones. Preoperative ureteral stents were indwelt in all the patients for 1-2 weeks. After dilation of the ureter with F8/9.8 rigid ureteroscope, the ureteral access sheath for flexible ureteroscope was inserted to the target ureter followed by flexible ureteroscope. Stones were fragmentized by holmium laser and the power was not more than 30 W (1.0-1.5 J/15-20 Hz). ResultsThe success rate of ureteroscopic insertion was 100% (37/37). The operation time ranged from 40 to 185 minutes with a mean of 73 minutes. After the operation, one patient had sepsis, and was cured after positive anti-infection treatment. No other serious complications occurred. Four and 8 weeks after surgery, the free-stone rate was 73.0% (27/37) and 86.5% (32/37) respectively. ConclusionThe flexible ureteroscopic lithotripsy is advantageous in less trauma, fewer complications, quick recovery and higher free-stone rate. It can be used to treat renal calculi of over 2 cm in diameter selectively.