Fate of residual fragments after successful extracorporeal shock wave lithotripsy

Purpose: The aim of the present study was to investigate the reason residua l fragments from upper urinary tract calculi failed to clear after Successf ul extracorporeal shock wave lithotripsy (ESWL). Methods: Risk factors were analyzed in 161 patients with residual fragments (less than or equal to 4 mm) that had remained for more than 3 months afte r ESWL. The factors examined in the present study were gender, a history of urolithiasis, the number, location and size of stones, hydronephrosis 3 mo nths after ESWL and bacteriuria before ESWL. The mean follow-up period was 20.0 months (range 6-69 months). Results: The overall stone-free rate was 14.3%. The stone-free rate in pati ents with multiple stones or hydronephrosis 3 months after ESWL was signifi cantly lower than that in patients without these conditions (P<0.05 and P<0 .01, respectively). The cumulative non-clearance rate in patients with hydr onephrosis was significantly higher than in patients without this condition (P<0.05). Results of Cox's proportional hazards model indicated that hydro nephrosis was the most important and only significant factor for failure to clear of the seven factors investigated (P<0.05). Conclusion: Hydronephrosis was most highly correlated with the fate of resi dual fragments after ESWL.