[Cholesterol content of bile-duct stones]

The cholesterol content of bile-duct stones from 40 patients after cholecystectomy was compared with 22 gall-bladder stones. There were 18 (82%) cholesterol-rich stones (cholesterol content more than 60% of dry weight) among gall-bladder stones, but only 12 (30%) among bile-duct stones. Eight bile-duct stones (20%) contained fibrous material, a further seven (18%) had a cholesterol-rich nucleus and cholesterol-poor outer layer. These findings indicate that residual fibres or small migrated gall-bladder stones can form the nidus for the growth of choledochal stones. The cholesterol content of bile-duct stones did not correlate with the age of the patient, time since cholecystectomy or cholesterol saturation of hepatic bile.