Extracorporeal Shock Wave Lithotripsy in Pediatric Patients Using a Late Generation Portable Lithotriptor: Experience at Children’s Hospital Boston Caleb P. Nelson,* David A. Diamond, Marc Cendron, Craig A. Peters and Bartley G. Cilento From the Departments of Urology, Children’s Hospital Boston and Harvard Medical School, Boston, Massachusetts, and University of Virginia (CAP), Charlottesville, Virginia Purpose: Kidney stones in children are increasing in incidence. The continued evolution of stone treatment modalities, including shock wave lithotripsy, makes the assessment of continuous outcomes essential. We describe contemporary shock wave lithotripsy outcomes in pediatric patients. Materials and Methods: A medical record review was performed of all patients younger than 20 years who underwent shock wave lithotripsy in 1998 to 2007. Patients were treated using a Dornier Compact Delta® lithotriptor with ultrasound and fluoroscopic imaging. Subjects were defined as stone-free if imaging within 12 months showed no evidence of stones with no additional treatment. Patient and treatment factors associated with successful outcomes were analyzed. Results: In 101 children a total of 114 treatment sequences were performed at a total of 150 shock wave lithotripsy sessions. Mean patient age was 10.5 years and 53% of the patients were girls. Mean stone diameter was 8 mm. Treatment was done for a solitary stone in 76% of cases, for 2 stones in 17% and for 3 or more in 7% with a mean shock count of 2,247. One, 2 and 3 or more treatment sessions were done in 78%, 16% and 6% of patients, respectively. The overall stone-free rate was 58.6%. However, the stone-free rate was only 12.5% after treatment sequences in 20 children with a history of anatomical urological conditions or surgery, while the stone-free rate in children without urological conditions was 67% (p 0.0001). Another factor associated with a decreased stone-free rate was stone size greater than 10 mm (25% vs 63%, p = 0.01). Complications included requiring acute reevaluation or treatment after 7% of shock wave lithotripsy sessions and 3.4% of patients required readmission. Conclusions: Extracorporeal shock wave lithotripsy is effective in many children with urolithiasis and it is well tolerated. However, in some children, particularly those with a history of urological surgery or congenital genitourinary conditions, success rates are low. These children may be best treated with other modalities. Key Words: kidney, kidney calculi, lithotripsy, abnormalities A lthough SWL is now an accepted modality for urinary tract stones in children, the introduction of SWL ther- apy in the pediatric population lagged well behind its widespread adoption in adults, probably because of concerns over the potential adverse effects of SWL on developing organ systems in children. 1,2 The first reports of pediatric SWL did not come until the late 1980s. 3,4 Since then, a number of investigators have reported good success after SWL using first-generation and second-generation lithotrip- tors. 5,6 More recently a number of smaller, portable lithotriptors have been developed but the efficacy of these newer devices in children is poorly described. Complicating efforts to eval- uate the effectiveness of SWL in pediatric patients is the small number of pediatric stone formers, continual changes in lithotriptor technology and in particular a lack of stan- dards for the relative quantification of lithotriptor power and efficiency, 7 which have made comparisons of outcomes among machines difficult. We evaluated the effectiveness of SWL treatment in a pediatric population using the Dornier Compact Delta por- table lithotriptor by reviewing the institutional experience with these procedures in the last 10 years. METHODS After receiving institutional review board approval we per- formed a computerized record and billing review to identify all pediatric patients who underwent SWL for upper urinary tract stones between 1998 and 2007. Patients were included if they were younger than 20 years at the initial procedure. In general our practice with pediatric stones is to observe nonobstructing stones smaller than 5 mm. Treatment is reserved for obstructing stones, stones greater than 5 mm or stones that increase in size on serial imaging. The primary outcome was stone-free status on post-pro- cedure imaging. Because in some patients stone fragments or debris passed in delayed fashion, we considered a patient to be stone-free if stone-free status was identified on any postoperative imaging up to 12 months after the procedure, even when earlier postoperative images showed a residual stone burden. The 12-month cutoff was used because the timing of post-SWL imaging was highly variable in the study Study received institutional review board approval. * Correspondence: Department of Urology, Children’s Hospital Boston, 300 Longwood Ave., Boston, Massachusetts 02468 (tele- phone: 617-355-3338; e-mail: caleb.nelson@childrens.harvard.edu). 0022-5347/08/1804-1865/0 Vol. 180, 1865-1868, October 2008 THE JOURNAL OF UROLOGY ® Printed in U.S.A. Copyright © 2008 by AMERICAN UROLOGICAL ASSOCIATION DOI:10.1016/j.juro.2008.05.085 1865