Report on the Safety and Efficacy of the Medstone 1050 Lithotripter

Abstract

This report summarizes the results through November 1987 of the ongoing multicenter trial of a new lithotripter, the Medstone 1050. This lithotripter employs a shock wave generator, but eliminates the water bath, has computer-derived positioning, and can localize stones with either plain radiographs or ultrasound. Three hundred and six patients with 531 stones were available for evaluation of immediate efficacy. Stone size was 10 mm or less in 67% of cases, 10 mm to 20 mm in 28% of cases, and greater than 20 mm in 5% of cases. Sixty-two percent of stones were calyceal, 25% pelvic, and 13% ureteral. Successful fragmentation occurred (defined as no fragment larger than 4 mm) in 90.5% of patients, and in 92.7% of individual stones, including a retreatment rate of 4%. No significant variation in success rate could be related to patient weight, stone size, or location. Follow-up evaluation of the first 165 patients revealed no clinically significant laboratory abnormalities. The average hematocrit changed from 41% to 39%, possibly due to hemolysis. Only a single 2 cm hematoma was found on ultrasound, and no transfusions were administered. Significant renal colic occurred in 25% and temporary obstruction in 12%. Renal scan or excretory urography was performed at three months following treatment in 135 of 165 patients (82%). One treated kidney was found to have diminished function due to a residual obstructing stone fragment.