A randomized outcomes trial of ureteral stents for extracorporeal shock wave lithotripsy of solitary kidney or proximal ureteral stones.

PURPOSE: Routine use of ureteral stents before extracorporeal shock wave lithotripsy of kidney stones between 10 and 20 mm. is controversial. We conducted a prospective randomized clinical trial to evaluate the outcome of ureteral stents for treating solitary kidney stones between 10 and 20 mm. or solitary proximal ureteral stones less than 20 mm. with shock wave lithotripsy.

MATERIALS AND METHODS: A total of 97 patients who met the aforementioned criteria were randomized between March 1994 to July 1997 into group 1-no stent, group 2-a 4.7Fr multi-length stent and group 3-a 7Fr multi-length stent. The patients were treated with the Dornier HM3 lithotriptor (Dornier Medical Systems, Inc., Marietta, Georgia) and monitored for stone-free rate, number of days lost from work, number of patients requiring rehospitalization, emergency room visits, irritative voiding symptom score and pain symptom score.

RESULTS: Objective outcome was obtained from 91 patients based on a followup of at least 3 months. The overall stone-free rate was 80%, with a re-treatment rate of 7%. The number of days lost from work was approximately 2, with no significant differences among individual groups or subgroups. The hospitalization rate and number of emergency room visits in group 1 (22%) were statistically higher compared to groups 2 (7%) and 3 (7%). The irritative voiding symptom score was statistically higher in the stented groups 2 and 3 compared to the nonstented group 1.

CONCLUSIONS: Although ureteral stents are associated with more irritative symptoms, their use resulted in fewer hospital readmissions and emergency room visits compared to when no stent was used to treat solitary kidney stones of 10 to 20 mm. or solitary proximal ureteral stones less than 20 mm. Size 4.7Fr stents may be preferable over 7Fr stents when used in conjunction with shock wave lithotripsy.