Does degree of hydronephrosis affect success of extracorporeal shock wave lithotripsy for distal ureteral stones?

OBJECTIVES

To investigate the relation between the degree of stone-induced hydronephrosis and the outcome of shock wave lithotripsy in patients with distal ureter stones.

METHODS

A total of 215 patients with a solitary distal ureter stone with or without hydronephrosis were treated with shock wave lithotripsy. The degree of hydronephrosis was determined by renal ultrasonography. The patients were divided into four groups according to the degree of stone-induced hydronephrosis. Group 0 (44.2%) had no urinary system dilation, group 1 (32.5%) had mild dilation, group 2 (16.3%) had moderate dilation, and group 3 (7%) had severe dilation. The patients were treated with the Dornier MFL 5000 lithotripter. The results were compared in terms of the stone-free rates, number of shock waves, number of sessions, incidence of complications, number of secondary interventions, and time to stone clearance.

RESULTS

The mean stone size was 11.2 +/- 2.5 mm. In the hydronephrotic group, the stone-free rate was 74% compared with 83% in patients without hydronephrosis (P = 0.27). The mean time to stone clearance was 16.3 +/- 9.2 days. The differences among the four groups in terms of stone size and treatment outcome were not significant. However, the presence of hydronephrosis was significantly associated with repeat treatment (2.2 versus 1.6, P <0.001) and prolonged clearance time (18.7 versus 15.4 days, P <0.001).

CONCLUSIONS

The results of our study have shown that in patients with solitary distal ureter stones, the degree of hydronephrosis caused by the stone does not affect the overall treatment success with shock wave lithotripsy. However, stones in obstructed systems tended to require repeat treatment and prolonged time for stone clearance.