Stratification of bile in gallbladder and gallstone formation

The essential role of the gallbladder in gallstone formation should not be underestimated, as cholesterol stones originate in the gallbladder. The possible significance of stratification of bile in the gallbladder has been studied using recently proposed lithogenic parameters, such as triangular co-ordinates, lithogenic index and cholesterol saturation index. Bile becomes less lithogenic as the concentrating process in the gallbladder progresses. The concentrating activity of the gallbladder seems to differ considerably for each bile constituent. Bile salts are most concentrated in the gallbladder, followed by phospholipids and cholesterol. The presence of a selective absorption process in the gallbladder is suggested. As the gallbladder diminishes the lithogenicity of bile during storage, its role probably lies in its ability to interrupt the enterohepatic circulation leading to the production of lithogenic bile as well as providing a recess to ensure continuous growth of stones.