Extracorporeal shockwave lithotripsy for solitary distal ureteral stones: does the degree of urinary obstruction affect success?

Abstract

Extracorporeal shockwave lithotripsy (SWL) is a safe and effective way to treat stones in the distal ureter, but the impact of urinary obstruction on outcome is not clear. We investigated the relation between the degree of stone-induced urinary obstruction and the outcome of SWL treatment in patients with solitary distal ureteral stones. A series of 165 consecutive patients with solitary distal ureteral stones underwent SWL (Multimed 9200 Lithotriptor, Elmed Medical Systems, Turkey) between October 2002 and September 2003 at two separate centers. Distal ureteral stones were defined as those located below the lower border of the sacroiliac joint. Patients were divided into four groups according to the degree of stone-induced urinary obstruction: group I (N = 62) had no urinary system dilation; group II (N = 40) had mild dilation, group III (N = 35) moderate dilation, and group IV (N = 28) severe dilation. In addition to degree of obstruction, stone size, average fluoroscopy time, total number of shockwaves applied, number of sessions required to achieve stone-free status, and stone clearance time were recorded. Treatment failure was defined as persistence of fragments after three SWL sessions. Overall, 152 (92.1%) of the patients became stone free after SWL. There were no statistically significant differences among the groups with respect to any of the factors studied. In cases where there is a solitary calculus in the distal ureter, the degree of urinary obstruction caused by the stone does not affect the success of stone clearance with SWL.