Impact of the degree of hydronephrosis on the efficacy of in situ extracorporeal shock-wave lithotripsy for proximal ureteral calculi

Objective. We conducted a prospective randomized study to investigate the relation between the degree of stone-induced hydronephrosis and the outcome of extracorporeal shock-wave lithotripsy (ESWL) in patients with lumbar ureter stones. Material and methods. A total of 284 patients with solitary lumbar ureter stones with or without hydronephrosis were treated with ESWL. The degree of hydronephrosis was determined by means of renal ultrasound. Patients were divided into four groups according to the degree of stone-induced hydronephrosis. The results were analyzed by comparing stone-free rates, the number of shock waves, the number of sessions, the incidence of complications, secondary interventions and time to stone clearance. Results. The mean stone size was 11.4 +/- 2.6 mm. In the hydronephrotic group, the stone-free rate was 80.3%, compared to 89.1% in patients without hydronephrosis (p = 0.12). The mean time to stone clearance was 13.8 +/- 9.8 days. Differences among the four groups in terms of stone size and treatment outcome were not significant. However, the presence of hydronephrosis was highly associated with repeat treatment (2.4 vs 1.7 treatments; p < 0.001) and prolonged clearance time (16.2 vs 11.6 days; p < 0.001). Conclusions. In cases with solitary lumbar ureter stones, the degree of hydronephrosis caused by the stone does not affect the overall treatment success with ESWL. However, stones in obstructed systems are associated with a tendency for repeat treatment and a prolonged time for stone clearance.