Extracorporeal shock-wave lithotripsy: prevalence of renal stones 3-21 months after treatment.

One hundred and four (70%) of the first 148 patients who underwent extracorporeal shock-wave lithotripsy (ESWL) at the University of Florida were evaluated for persistent or recurrent renal stone disease. Radiographs obtained 3-21 months after treatment showed that 53 (50%) of 106 treated kidneys were free of stones. In 48 of the 53 kidneys that contained stones, the stones were residual fragments dating from the period immediately after ESWL. New stones had developed in only five kidneys. The 50% incidence of stone-free kidneys 3-21 months after ESWL is less than the 65-90% rate reported by other institutions in the United States and Europe. After stone removal by ESWL, new stone formation occurs at a rate of 5%, which is much lower than the expected recurrence rate of 37-50%.