The safety and efficacy of gallbladder extracorporeal
shock-wave
lithotripsy combined with 600 mg/day
ursodiol were examined in 85 patients with radiolucent
gallstones, 15 with lightly calcified
gallstones, and 12 with radiolucent stones pretreated for greater than or equal to 2 months with 600 mg/day
ursodiol. Results were compared with those of a well-matched
lithotripsy-eligible group of 32 subjects treated with
ursodiol alone (no
lithotripsy). Pretreatment with
ursodiol significantly improved while
gallstone calcification interfered with fragmentation. Small
gallstone size and number also aided fragmentation. Biliary
lithotripsy plus
ursodiol increased efficacy twofold compared with
ursodiol therapy alone (47% vs. 22% of subjects
gallstone free; P less than 0.02).
Gallstones did not disappear in any subject with calcified
gallstones (P less than 0.001) vs.
lithotripsy). Product-limit analysis showed that the efficacy for
gallstone dissolution increases in the following order:
ursodiol alone,
lithotripsy-
ursodiol,
lithotripsy-
ursodiol pretreated with
ursodiol (P less than 0.02, pairwise). Similar mean
gallstone-dissolution rate constants (stone size divided by time to disappear) of stone fragments and whole
gallstones during
ursodiol therapy suggest that most fragments disappear by dissolution not expulsion. This finding explains why fragmentation appears to be the key predictor of disappearance and even partial fragmentation accelerates
gallstone clearance.