RESUMEN
Between March 2000 and November 2003, 544 patient [374 males and 170 females] with ureteral stones were treated by ESWL using Storz Modulith SL-20 and Storz Modulith SL-X lithotriptors. Stones were located in the upper ureter in 308 cases, in the lower ureter in 204 cases and middle ureter in 32 cases. Stone sizes were 5-10 mm in 294 cases, 11-15 mm in 182 cases and 16-20 mm in 68 cases. The majority of the patients had single stones, while 43 cases had two or three stones. Pre-ESWL fixation of double-J stents was needed in 15.6%. The treatment voltage ranged between 15 and 18 kV. Mean duration of treatment was 35 minutes with average 3500 shocks. Patients required 2.2 sessions per stone. The overall stone free rate after six months was 73.6% [332 cases]. Stone size was the only statistically significant factor in the results of stone clearance. The stone free rates in patients with stones less than 10 mm, between 11-15 mm and 16-20 mm were 78%, 69.9% and 59.7%, respectively. There was no statistical significance for stone number or stone site in the results of stone fragmentation and clearance. Also, there was no significant statistical difference concerning the machine used. In conclusion, both Storz Modulith SL-20 and SL-X ESWL machines were equally effective. Stone size was the only statistically significant factor in the results of stone clearance