Extracorporeal shock wave lithotripsy.

Abstract

The first clinical application of extracorporeal SWL dates back to 1980. Since then the use of this method has spread widely and its indications have been extended progressively so that it way now be considered the treatment of choice in 80-90% of cases of ureterorenal lithiasis. Treatments without anesthesia or analgesics have been associated with an increase of retreatments from 5-14% (original HM3) to 45-60% (lithotripters not requiring anesthesia or analgesia). However, almost all lithotripter succeed in fragmenting stones sufficiently. The stone free rate varies with different lithotripters in the different series: 90-56% for stones of maximum diameter < 1 cm, 78-30% for stones of maximum diameter of 1-2 cm. and 52.5-10% for stones of maximum diameter of 2-3 cm. (the last figure was obtained with a piezoelectric lithotripter). Extracorporeal lithotripsy as monotherapy of staghorn stones has yelded a stone free rate varying between 31% and 55% with high percentages of residual fragments in about 50% of case of the various series. The stone free rate after treatment varies according to stone site: it is between 75% and 84% of caliceal stones for upper caliceal calculi and falls to under 60% for lower caliceal ones. The frequency of recurrences, that is, of new stones in patients stone free after SWL, is between 4% and 10% annually. Adding the percentage of true recurrences reported by the various authors at 19 to 42 months of follow-up (6.2-13.8%) to the fragment regrowth rate (17.2-22.3%) gives a total new stone rate of 23.4% and 36%. These figures are not greatly different from those reported in a population of untreated stone formers (10-15% per year). Extracorporeal lithotripsy seems thus not to influence lithiasis recurrence significantly.