Hepatopancreatic ampulla (of Vater) and sphincter of Oddi
Termination
The bile duct and the main pancreatic duct (of Wirsung) unite within the wall of the second part of the duodenum to form the ampulla, which opens at the major duodenal papilla on the posteromedial wall about 8-10 cm beyond the pylorus. The sphincter of Oddi (choledochal, pancreatic and ampullary parts) stays closed between meals, so hepatic bile backs up the cystic duct into the gallbladder; cholecystokinin relaxes it. The accessory pancreatic duct (of Santorini) opens at the minor papilla about 2 cm proximally.
Traced from the start
- Right hepatic ductLeft hepatic duct
- Gallbladder
- Common hepatic ductCystic duct
- Common bile duct (bile duct)
- Hepatopancreatic ampulla (of Vater) and sphincter of Oddi
Detail
- Site
- Posteromedial wall of the second part of the duodenum, 8-10 cm from the pylorus
- Control
- Cholecystokinin relaxes the sphincter and contracts the gallbladder; morphine causes sphincter spasm
- Shared channel
- Bile and pancreatic juice pass through a common segment, the basis of gallstone pancreatitis
When it goes wrong
Small stone impacted at, or passing through, the ampulla
Acute gallstone pancreatitis (epigastric pain radiating to the back, lipase more than three times normal), often with transient jaundice; with alcohol it is the commonest cause of pancreatitis in Australia
Periampullary carcinoma
Painless obstructive jaundice; occult bleeding mixed with pale stool produces 'silver stools' (Thomas's sign); prognosis is better than pancreatic head cancer because it obstructs and presents early
Endoscopic sphincterotomy at ERCP
Relieves obstruction and lets stones pass, at the risk of post-ERCP pancreatitis, bleeding and duodenal perforation
Practise this structure
1 question in the bank tagged Pancreas.