Utility of ureteral stent for stone street after extracorporeal shock wave lithotripsy

We reviewed the records of the 530 patients with urinary stones (renal stones: 243; ureter stones 287) who received extracorporeal shock wave lithotripsy (ESWL) (MFL5000; Dornier), from January 1995 to July 2002, retrospectively and determined whether the ureteral stent affected the incidence rate of stone street (SS). We also assessed the effect of ureteral stent on the subsequent management for SS. Forty patients (7.5%) developed SS. Twenty patients were inserted a ureteral stent prior to ESWL (stent group), and 20 patients were performed ESWL without a ureteral stent (in situ group). In the stent group, the most common (80.0%) location for SS was in the upper third ureter, while in the in situ group, SS mostly developed in the distal third ureter (60.0%). The incidence of SS did not differ significantly between the two groups when the size of renal and ureter stones was below 30 and 20 mm, respectively. When the renal stones were larger than above 30 mm, the incidence of SS in the stent group was significantly higher than that in the in situ group. SS disappeared spontaneously with stone passage in 10 of the patients in in situ group, but in only 1 patient in the stent group. In the stent group, 15 patients were treated for SS by removal of ureteral stent regardless of stone diameter. We conclude that ESWL should be performed without a ureteral stent when the stone diameter is below 20 mm. When the ureteral stent is thought to interfere with the delivery of stone fragments, the decision to remove it should be made as soon as possible.