Structural analysis of gallstones with thin-section petrographic microscopy: a study of 100 gallstones from Taiwanese patients.

Cholecystolithiasis is a common disease, making cholecystectomy a commonly performed surgical procedure. The gross appearance of gallstones differs from case to case. To classify gallstones on the basis of their structure, we randomly collected gallstones from 100 (64 of them women) of 3,289 patients who underwent cholecystectomy at our hospital. The stones were grossly classified into five major types: pure-cholesterol stones, combination stones, mixed stones, black stones, and calcium bilirubinate stones. We then used thin-section petrographic microscopic study (TSPMS) to inspect each stone under a polarizing microscope. Final classification of the stone depended on TSPMS findings. Of the 100 patients, 35 had pure-cholesterol stones, 12 had combination stones, 17 had mixed stones, 25 had black stones, and 8 had calcium bilirubinate stones; the stones from 3 patients could not be classified on TSPMS. Accurate structural classification of gallstones could be made by gross inspection with confirmation by TSPMS, a useful method of classifying gallstones.