Does size and site matter for renal stones up to 30-mm in size in children treated by extracorporeal lithotripsy?

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Objectives: To determine the safety and efficacy of extracorporeal shock wave lithotripsy (ESWL) in the treatment of pediatric nephrolithiasis and to analyze the impact of renal stone size and location on stone clearance.Methods: This was a retrospective case series of pediatric patients (14 years or younger) undergoing lithotripsy using a Dornier MPL 9000 echo-guided lithotriptor. Patients were identified using an international coding and indexing system (9th edition) and ESWL registry. One hundred five patients were treated from January 1990 to December 2001. Stone clearance was assessed at 1 and 3 months. A stone-free state was defined as no radiologic evidence of stone or fragments 3 mm or less. Treatment failure was analyzed to find any correlation with stone size and site.Results: The overall stone-free rate was 95%. The treatment failed in 5 patients, who subsequently required ancillary procedures. Three patients received one session of ESWL, after which they were lost to treatment and were not analyzed further. Four of the five patients with treatment failure had a double-J stent; the stones were located in the lower pole calix in 2, renal pelvis and lower pole calix in 1, and at the ureteropelvic junction in 2 patients. The mean stone size in the treatment failure group was 15.88 mm compared with 14 mm in the stone-free group. The complication rate was 8%, but only 3 patients required admission.CONCLUSIONS: ESWL is highly effective for pediatric renal stones, with minimal morbidity. Stone clearance is not adversely affected by a stone size up to 30 mm; however, lower pole caliceal stones and stones impacted at the ureteropelvic junction have relatively poorer clearance. Eighty percent of patients who failed to clear their stones had a double-J stent.