Fate of residual fragments after successful extracorporeal shock wave lithotripsy.

Abstract

The aim of the present study was to investigate the reason residual fragments from upper urinary tract calculi failed to clear after successful extracorporeal shock wave lithotripsy (ESWL). Risk factors were analyzed in 161 patients with residual fragments (< or = 4 mm) that had remained for more than 3 months after ESWL. The factors examined in the present study were gender, a history of urolithiasis, the number, location and size of stones, hydronephrosis 3 months after ESWL and bacteriuria before ESWL. The mean follow-up period was 20.0 months (range 6-69 months). The overall stone-free rate was 14.3%. The stone-free rate in patients with multiple stones or hydronephrosis 3 months after ESWL was significantly lower than that in patients without these conditions (P < 0.05 and P < 0.01, respectively). The cumulative non-clearance rate in patients with hydronephrosis was significantly higher than in patients without this condition (P < 0.05). Results of Cox's proportional hazards model indicated that hydronephrosis was the most important and only significant factor for failure to clear of the seven factors investigated (P < 0.05). Hydronephrosis was most highly correlated with the fate of residual fragments after ESWL.