Utility of biliary microscopy for the prediction of the chemical composition of gallstones and the outcome of dissolution therapy with ursodeoxycholic acid

Abstract

To learn whether microcrystalline solids in bile could predict gallstone composition, the findings determined by polarizing microscopy of gallbladder bile were related to stone type at cholecystectomy in 53 patients. Cholesterol crystals were present in 36 of 39 cholesterol stone biles and absent in 12 of 14 biles from noncholesterol stones. Fifteen cholesterol stones (eight radiopaque) contained calcium carbonate, and characteristic vaterite microspheroliths were observed in 53% of their biles. In another study, crystals in basal duodenal bile were related to the outcome of gallstone dissolution treatment with ursodeoxycholic acid, 10 mg/kg · day. In 39 patients treated for 1 yr, efficacy (complete gallstone dissolution) was 41% overall and 52% in patients with stones ≤ 10 mm in diameter. In connection with the findings of biliary microscopy, efficacy was 93% in 14 patients with cholesterol crystals in bile, and 27% in 11 patients with microspheroliths in bile. Cholecystectomies in 9 patients with dissolution failure revealed 4 cases of noncholesterol stones and 5 cases (including 3 with on-therapy calcification) of calcium carbonate-rich cholesterol stones with a surface/interior mineral ratio >3. The results confirm that cholesterol crystals in bile are a sensitive measure of cholesterol gallstones. They also show that vaterite microspheroliths in bile indicate the presence of calcium carbonate in gallstones. Both findings suggest that biliary crystals reflect gallstone composition, and it is demonstrated that this information is useful in predicting the success or failure of cholelitholysis with ursodeoxycholic acid. Finally, the data show that radiologically undetectable stone calcification reduces the probability of dissolution, and that the calcified structures appearing in some stones during treatment are composed of calcium carbonate.