Are obstructing ureteral stones more difficult to treat with extracorporeal electromagnetic shock wave lithotripsy?

In situ extracorporeal shock wave lithotripsy (ESL) has increasingly become accepted for the treatment of ureteral stones. However, treatment success is negatively affected by stone impaction or associated urinary obstruction. In order to assess the impact of obstruction on the outcome of in situ ESL, we reviewed the results in 503 patients treated in this way. The presence and severity of urinary obstruction was defined prior to ESL, being classified as no or mild obstruction (Group I) and moderate or severe obstruction (Group II). The stone-free rate in the nonobstructed group was 90%, whereas it was 85% in the obstructed group (P > 0.005). While all of our patients were treated on an outpatient basis, two patients in Group I and four patients in Group II required hospitalization with the diagnosis of pyelonephritis. All six patients were treated successfully with appropriate measures. No other serious complication occurred that required hospitalization. We conclude that urinary obstruction does not affect stone disintegration or passage and suggest that in situ ESL should be the treatment of choice in ureteral stones.