Extracorporeal shock wave lithotripsy in morbidly obese patients.

Management of urolithiasis in morbidly obese patients is usually associated with higher morbidity and mortality compared to nonobese patients. In morbidly obese patients, since the kidney and stone are at a considerable distance from the skin (compared to nonobese patients), difficulty may be encountered in positioning the patient so that the stone is situated at the F2 focal point of the lithotriptor. Using various aids, such as the extended shock pathway and abdominal compression, we treated 81 patients weighing more than 300 pounds using the Medstone STS tubless second generation lithotriptor. The stone-free rate at 3 months or longer was 68%, with another 10% having asymptomatic fragments of 4 mm. or less in diameter. Thus, a clinical stone-free rate of 78% was achieved. The retreatment rate was 11% and the post-lithotripsy secondary procedures rate was 3%. Since these results are comparable to those obtained when treating patients less than 300 pounds, extracorporeal shock wave lithotripsy can be used successfully to treat urolithiasis in morbidly obese patients.