Chemical composition of gallbladder sludge in patients after marrow transplantation

Objectives: Gallbladder sludge develops in approximately 70% of patients after bone marrow transplantation (BMT). Sludge often develops in these patients without known predisposing factors, such as fasting or narcotic use. In this study, we examined the chemical composition of sludge in BMT patients. Methods: Gallbladder content samples from 15 patients were obtained at autopsy. Presence or absence of sludge was determined by examination of gallbladder contents. Sludge samples were examined with direct and polarizing microscopy and assayed for cholesterol, bilirubin, and calcium content and for the presence of a calcium-binding protein. Results: On microscopic examination, cholesterol monohydrate crystals were almost completely absent. Calcium bilirubinate crystals were present in large amounts in all samples. Calcium-ceftriaxone crystals were found in two patients who had received ceftriaxone. A large proportion of the sludge (84.6%) was found to be 'unmeasurable residue.' Of this part, 5-30% was accounted for by a calcium- binding protein. Conclusions: We conclude that gallbladder sludge in patients after marrow transplantation consists primarily of 'unmeasurable residue,' calcium bilirubinate, and a calcium-binding protein. Cholesterol crystals are almost absent. We conclude that formation of gallbladder sludge in these patients could serve as a model for studying the pathogenesis of pigment gallstones.