The most common site for a stone in the biliary tract is the gallbladder (A). Stones may also form in intrahepatic bile ducts (B). Stones may pass into the common bile duct (C) to cause obstruction. A stone can pass down to where the bile duct and pancreatic duct join (D) and produce a pancreatitis. A stone may pass out through the ampulla of Vater into the duodenum (E).

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