The advent of extracorporeal shock wave lithotripsy (ESWL) as a noninvasive technique has revolutionalized the management of urinary tract calculi. The technique is considered a safe and effective treatment for urinary lithiasis in adults. However, the application of this modality of treatment in children has followed rather slowly. Although evidence has accumulated on the efficacy of ESWL in treating calculi in children, 1-3 the effects of shock waves on the pediatric urinary tract have still not been adequately researched. Indeed, ESWL is considered by some to be contraindicated in children. 4 As a contribution to the growing data in this field, we present a retrospective study on our use of a second-generation lithotripter (Siemens Lithostar) in the treatment of renal calculi in children in Saudi Arabia. Patients and MethodsBetween January 1993 and December 1998, 67 children with stones in the urinary tract were treated by ESWL, using the Siemens Lithostar lithotripter. There were 38 boys and 29 girls, and their ages ranged from 5-16 years (mean 12.9). Prior to shock wave treatment, all patients underwent renal and bladder sonography, intravenous urography (IVU), blood tests for renal function, coagulation profile, urine analysis and urine culture. Patients with allergy had a dimercapto succinic acid (DMSA) renal scan.Of the 63 patients, 53 (79%) presented with pain; 8 with microhematuria, and one with gross hematuria. Urine culture was positive in 8 children (12%), and they were given appropriate antibiotic therapy before stone treatment. Stone disease was associated with horseshoe kidney in one case, while three other children had previously undergone surgery for posterior urethral valve, pelvi-ureteric junction obstruction, and meatal stenosis, respectively.There were 56 renal stones (37 pelvic, 16 calyceal, and 3 staghorn). Eleven children had ureteric and three had bladder stones. Only three children had radiolucent calculi, with bilateral renal calculi in three others. The stone size ranged from 4 to 40 mm (mean 16). ESWL was done as an outpatient procedure in 20 children. Fifteen patients with bulky stones (>20 mm) had internal stents before treatment, and three had placement of ureteric catheters for visualization of radiolucent stones. General anesthesia was used in 19 patients, usually those below the age of 12 years. The rest received pethidine for sedation and analgesia. The mean number of shocks delivered was 3000, and the generator voltage ranged from 16 to 19 kV. Most of the patients required only one ESWL session (mean 1.7).Plain abdominal x-ray was done on the day after treatment and repeated monthly in the outpatient department. Patients with radiolucent stones and those with bulky stones were followed with ultrasound scans. A patient was regarded as stone free if no stone fragment was discernible, and the time of this status was noted. A "successful outcome" was defined to include stone-free patients and those patients with stone fragments less than 4 mm, which were deemed passable. Results...