Sonogram of Biliary Dilatation in Children

The biliary trees descend from the canaliculi at the hepatocytes in the liver. Bile drains from this level into intrahepatic ducts, smaller ducts combine to form the segmental bile ducts which within the liver gradually enlarge and merge to the right and left hepatic ducts. The right and left hepatic ducts join together to form the common hepatic duct (CHD) at porta hepatis. The common bile duct (CBD) is formed by the junction of the cystic duct with the CHD. The CBD traverses through the head of the pancreas entering the duodenum through the Sphincter of Oddi at the Ampulla of Vater. Prior to draining into the duodenum, the CBD is joined by the pancreatic duct. A smaller accessory pancreatic duct and sphincter is usually present (but rarely visible by sonography ) from the dorsal pancreatic embryologic rotation. (Fig. 1)