An evaluation of 646 stone patients treated on the HM4 extracorporeal shock wave lithotriptor.

Extracorporeal shock wave lithotripsy (ESWL) has become the preferred treatment modality for the majority of urinary tract calculi. This form of treatment boasts excellent patient acceptance and has significantly reduced the need for surgical intervention. An evaluation of our first 646 patients undergoing 722 ESWL treatments at Walter Reed Army Medical Center revealed an overall stone-free rate at 1 and 3 months of 52% and 79%, respectively. The exact location of each stone within the kidney and ureter further determined the stone-free rates at 1 and 3 months. Stone-free rates at 3 months ranged from 89% for renal pelvic stones to 64% for lower pole caliceal stones. Upper third ureteral stones treated in situ without stenting resulted in a 74% stone-free rate at 3 months. This rate increased to 85% when these patients were stented and treated in situ. Although statistically insignificant, when the upper third ureteral stones were manipulated into and treated in the renal pelvis (31% of our patient population) the 3-month stone-free rate increased to 87%. Attempts were made to stent all ureteral stones before treatment. The stone-free rate at 3 months was 86% for mid third ureteral stones and 81% for lower third ureteral stones. The overall retreatment rate was 11.8% with a complication rate of 7.6% and a 6.3% post-ESWL intervention rate (open or percutaneous surgery, stent or percutaneous nephrostomy placement).