Between December 1989 and July 1991, 29 patients with bladder stones were treated on the MPL 9000 extracorporeal shock wave lithotriptor using ultrasound for localisation. The mean stone dimensions were 22.65 x 15.17 mm (< 400 mm2 in 20 patients); 75% of patients required only 1 ESWL session but the largest stone (2025 mm2) required 3. Whilst larger stones tended to require more shock waves, linear regression analysis showed a poor fit and factors other than size (operator experience and stone hardness) may determine the number of shock waves required. Satisfactory fragmentation was obtained in all patients. All were treated under intravenous analgesia without anaesthesia. Three patients also had outflow obstruction and were treated by transurethral resection of the prostate (TURP) on the day after completing ESWL. ESWL prior to TURP reduces the morbidity and operating time associated with endoscopic therapy of bladder stones. Macroscopic fragments remaining after ESWL can be washed out at TURP.

The choice of treatment for patients with ureteric stones is critical but will vary depending on the individual's circumstances, the availability of equipment, costs and time required to perform the procedure. The results obtained using ESWL for ureteric stones improved considerably over the course of the study as a result of experience and refinement of the technique. Stones located in more difficult systems such as in kidneys with a thin cortex and those located above the ischial spine were no longer subjected to ESWL. Audit of the results obtained following treatment allows identification of problem areas, alerts physicians to alternative methods of treatment and gives an objective quantification of experience, assisting rational decision making with consequent improved success.

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