Cholesterol microlithiasis: bacteriology, gallbladder bile and stone composition.
It is not known whether microcalculi possess structural differences compared with larger stones or whether they represent simply an earlier stage in stone disease. We carried out a controlled study on 10 patients affected by gallbladder cholesterol microlithiasis (CM). In all patients, samples from all parts of the stones were studied by X-ray diffraction and by infrared spectrophotometry. Bile analysis was carried out to determine cholesterol, phospholipid and total bile acid content. The cholesterol saturation indices (C.S.I.) were calculated. In all samples, bacterial bile culture was carried out. The results were compared with those of 10 patients who had undergone cholecystectomy for large cholesterol stones, and for 10 patients who had undergone abdominal surgery but without biliary pathology. Patients in these latter groups were matched with the first according to sex and age. Microcalculi proved to be layered (nucleus and external layer) in only 2 cases and larger stones in 9; cholesterol was seen to be the principal crystalline component in all cases. Traces of bilirubin were found in 7 CM and in the nuclei of 5 larger stones. These results show that the structural composition of microcalculi is similar to that of the nucleus of larger stones. No substantial differences exist, however, between the two groups of patients regarding the other parameters taken into consideration.