Composition of intrahepatic calculi. Etiological significance.

Gallstones in intrahepatic (N = 42) and extrahepatic (N = 22) bile ducts and gallbladder (N = 23) were subjected to chemical analysis modified to suit the analysis of brown pigment stones with the aim of determining if stone location at surgery influenced stone composition. Dimethylsulfoxide-acetone-1 N HCl (90:9:1, v/v/v) was used to dissolve gallstone specimens. Intrahepatic calculi were divided into two groups, ie, nine cholesterol stones and 33 brown pigment stones. Cholesterol stones in the intrahepatic bile ducts had a similar composition to those in the gallbladder and extrahepatic bile ducts, suggesting a similar pathogenesis wherever formed throughout the biliary tract. Intrahepatic brown pigment stones contained significantly less bilirubin (P less than 0.001) and more cholesterol (P less than 0.05) by chi-square analysis than brown pigment stones found in the extrahepatic bile ducts, suggesting that the site of formation affects stone composition and modifies stone pathogenesis.