Preoperative stenting for ureteroscopic lithotripsy for a large renal stone.

A large renal stone can be treated ureteroscopically, but the treatment often requires more than one procedure. The use of stenting before ureteroscopy was recently reported. The present study investigated the effectiveness of preoperative stenting before ureteroscopic lithotripsy for large (>15 mm) renal stones. A ureteral stent was intentionally inserted in 25 patients undergoing ureteroscopic surgery. A group of 36 non-prestented patients was used as control. Median stone diameter was 21 mm in both groups. Pre-ureteroscopy stenting significantly improved the stone-free rate, defined as stones <2 mm and <4 mm (P < 0.05), whereas it did not significantly improve the stone-free rate defined as 0 mm (P = 0.12). The uretereoscopy success rate was 72.0% in the stented and 55.6% in the control group (P = 0.09). A 14/16-Fr ureteral access sheath was successfully inserted in 94.7% of the stented patients, and 74.2% of the non-stented patients (P < 0.05). Our findings showed that preoperative stenting is effective for dilation of the ureter, and also to facilitate the insertion of a ureteral access sheath in patients undergoing ureteroscopic lithotripsy for large renal stones.