Percutaneous ultrasonic lithotripsy (PUL) after shock wave lithotripsy (SWL) failure

Shock wave lithotripsy (SWL) is an attractive initial treatment for nephrolithiasis. Unfortunately, a significant number of stones are resistant to SWL therapy and require subsequent percutaneous ultrasonic lithotripsy (PUL) for definitive treatment. Our objective was to determine if previous SWL had adverse effects on PUL success and if there were differences between the patients undergoing primary PUL and those undergoing PUL after SWL failure.

In 2001, 108 PULs were performed at our institution, of which 40 (37%) were performed after SWL failure. Stone location, anesthesia time, stone composition and size, and complication rates were compared between patients who had PUL alone and those who underwent PUL after SWL failure. Anesthesia time was considered a reflection of technical difficulty of the case.

Stone composition differed between the SWL failure and primary PUL groups. Cystine stones were found to be more common in the ESWL failure group and calcium oxalate monohydrate stones more common in the primary PUL group. There was not a statistically significant difference in stone size, anesthesia time or complication rates, between the PUL alone and PUL after SWL failure groups.

PUL remains a reliable and safe treatment of nephrolithiasis. Prior SWL does not affect efficacy, technical difficulty, or postoperative complications of subsequent PUL. Based on our data, prior SWL should not be considered a negative factor in PUL outcomes. Stone composition should be considered a prognostic indicator of SWL failure and alert the surgeon that primary PUL may be indicated.