6 the stones are most commonly located within the

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and the remaining 10% pure cholesterol. 6
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The stones are most commonly located within the gallbladder, but can on occasion be found within the common bile duct or the liver or to have migrated into the intestinal tract. These findings are in stark contrast to those in other regions of the world, such as Southeast Asia, where the majority of biliary calculi are of the pigment variety and are most commonly located within the liver itself and not the gallbladder. Such variation also applies to the overall incidence of gallstone disease. In the United States about 12% of, the population has cholelithiasis, with more than 950,000 new cases diagnosed each year, while in East Africa and other selected Third World countries the incidence is as low as 2% to 3%. The risk of developing biliary calculi throughout America and Western Europe is directly proportional to a person’s age and sex. While children and adolescents rarely have gallstones, by the seventh decade of life 10% of men and 25% of women have documented cholelithiasis. CHOLESTEROL-ENRICHED GALLSTONE FORMATION The exact mechanism by which gallstones are formed is not fully understood, but calculi are likely the result of a complex, multifaceted alteration in hepatobiliary function. CHOLESTEROL-SUPERSATURATED BILE An early event in the process of gallstone formation is a change in the composition of bile, specifically a relative increase in the cholesterol content. Normally bile is an isotonic combination of water, electrolytes, and organic macromolecules that is actively secreted by the liver. Designed to aid in the solubilization (emulsification) and subsequent absorption of dietary fats, the solute composition of bile includes bile salts, cholesterol, and phospholipids, predominantly phosphatidylcholine (lecithin). As the molar ratio of cholesterol relative to either bile salts or phospholipid deviates from a relatively narrow range, the cholesterol solubilization capacity of bile is exceeded, resulting in rapid cholesterol crystal formation. GALLSTONE NUCLEATION Once bile has become supersaturated with cholesterol, the formation of a cholesterol-enriched gallstone presumably begins with a nucleation event. The precipitation of crystalline cholesterol is thought to occur via either the fusion or implosion of cholesterol-rich vesicles. A variety of different crystal shapes have been recently identified in bile samples from numerous patients with gallstones.7 These distinct cholesterol structures, including arcs/needles, spirals, tubes, and plates, may represent different stages in the nucleation process, as well as the existence of different cholesterol crystallization pathways. GALLBLADDER AND FOREGUT MOTILITY Gallbladder stasis has long been associated with the formation of gallstones. Beyond the intuitive sense that a stagnant pool of supersaturated bile must promote nucleation and stone growth, there is a growing body of data to support the concept. Specifically, investigators have demonstrated that the volume of bile flow through the gallbladder during the postprandial period
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  • Winter '18
  • Jane doe
  • bile duct, Hepatology, Gallstone

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