Does pre-treatment with bile acids enhance efficacy of biliary extracorporeal shock wave lithotripsy?

To determine the effect of chenodiol and ursodiol pre-treatment prior to shock wave lithotripsy of gallstones, two groups of 50 gallbladder stones (n = 100), obtained at cholecystectomy, were matched according to their size, shape and weight. All stones were stored in a bile perfused gallbladder model for two weeks. In the first group (A), serving as control, native bile was used, whereas in the other group (B), ursodiol- and chenodiol-enriched bile was perfused, both bile acids at therapeutic concentrations. After two weeks of pre-treatment, electromagnetic shock wave lithotripsy (19 kV, 1 Hz) was performed until stones were fragmented to a size smaller 2 mm. Neither stone density, as assessed by computed tomography, nor their cholesterol content were different in group A and B. A trend towards higher fragmentation efficacy was observed for stones < 15 mm and for those with a CT-density < 100 HU. No influence of either stone shape (rounded vs. angular) or cholesterol content was observed with regard to fragmentation efficacy. Comparing the number of shock waves (SW) required for fragmentation (< 2 mm) there was no significant difference between group A (1850 +/- 1300 SW) and group B (1970 +/- 1500 SW, n.s.). These in vitro results do not support a significant role of bile acids as a rationale pre-treatment prior to lithotripsy of gallstones.