Extracorporeal shock wave lithotripsy of ureteral stones: clinical experience and experimental findings.

ESWL of impacted ureteral or caliceal stones is not as successful as expected. To study this problem a model for extracorporeal shock wave lithotripsy of ureteral stones has been designed. After initial fragmentation of the outer shell of impacted stones during the first series of shock wave application those fragments are kept in place by external mucosal contact, creating a lot of new interfaces. Absorption or reflection of shock wave energy within this fragmented shell seems to be responsible for the poor success rate in these cases. In regard to our experimental and clinical results we advise pushing ureteral stones back into the renal collecting system by means of a ureteral catheter.