Extracorporeal shock wave lithotripsy retreatment ("stir-up") promotes discharge of persistent caliceal stone fragments after primary extracorporeal shock wave lithotripsy.

A prospective randomized study was performed to compare the results of piezoelectric extracorporeal shock wave lithotripsy (ESWL) retreatment versus surveillance only in 50 patients with persistent caliceal stone fragments after primary ESWL for renal calculi. After a 3-month followup significant decreases in residual debris were observed in the retreated group, while changes in the control group were negligible. Considering the low morbidity of outpatient ESWL with a pain-free, second generation lithotriptor, ESWL retreatment of completely fragmented but persistent stone debris appears to be justified to render the kidney stone-free.