Differences in gallstone structure in primary common bile duct lithiasis and gallbladder lithiasis.
Some differences between gallbladder lithiasis and primary common bile duct lithiasis are described. Microbiological cultures and biochemical analyses were carried out on the bile of two groups of patients: 27 suffering from gallbladder and 5 from primary common duct lithiasis. The microstructure and composition of gallstones were also examined by polarized light microscopy and X-ray diffraction. Women predominated in gallbladder lithiasis but not in primary common duct lithiasis group (P less than 0.05) and body weight was higher in the former group (P less than 0.02). Primary common duct lithiasis patients had a higher, although not significant, incidence of duodenal diverticulosis (P = 0.15), and a higher incidence of E. coli-positive cultures in bile (P less than 0.001). No significant difference in the biochemical composition of the bile was found between the groups. Brown pigment stones predominated in primary common duct lithiasis, while cholesterol stones did in gallbladder and secondary common duct lithiasis (P less than 0.0001). Stones formed in the gallbladder generally show linear, radial growths of cholesterol crystals, while those from the common duct present a polystratified, concentric deposition of microgranules composed mainly of pigmentary salts. These differences should be taken into account as additional criteria in the differential diagnosis between primary and secondary common duct lithiasis, as the classical criteria for diagnosing of the former greatly underestimate its actual incidence. The distinction between primary and secondary common duct lithiasis is of practical significance, since each entity requires different treatment.