[An investigation of factors associated with failure of extracorporeal shock wave lithotripsy for ureteral calculi].

In this study, we attempted to determine which patients with ureteral calculi are likely to have an unsuccessful outcome for extracorporeal shock wave lithotripsy (ESWL). The records of 388 patients with ureteral calculi treated with ESWL at Ijinkai Takeda General Hospital between January 1997 and December 1998 were retrospectively reviewed. Three hundred seventeen patients had been treated with ESWL alone (single session 156, multiple sessions 161) and 71 with transurethral ureterolithotripsy (TUL) due to failure of ESWL. We compared these two groups by multivariate logistic regression analysis, which revealed that (1) middle and lower ureteral calculi, (2) stones > 8 mm, (3) moderate to severe hydronephrosis and (4) failure of the first session ESWL were factors associated with poor outcome of ESWL. Although each predictive value of these factors was relatively low (29.6-38.6%), the rate of failure of ESWL was 85.0% when patients had all four factors. We therefore recommend an early change in treatment modality to TUL for patients with ureteral calculi when all four risk factors listed above are present.