Composition of biliary microcalculi studied with infrared spectrophotometry.

The chemical composition of biliary microcalculi obtained at 20 consecutive cholecystectomies was investigated with infrared spectroscopy. This method permits qualitative and quantitative analysis also of substances such as bilirubin which often remain in amorphous states. A PYE UNICAM spectrophotometer was used, with KBr pellet technique. A bile sample from each patient was taken for bacteriologic examination. The study confirmed previously observed high incidence of pigment microcalculi (60%). Calcium palmitate was more common (in 15% of all the studied microliths and 25% of the pigment type) than in reports in the literature concerning larger gallstones. Calcium carbonate was present in only 10%. These findings suggested pathogenetic peculiarities of microlithiasis, as did the high incidence of positive bacteriologic tests.