Sphincter of Oddi

By Barbara Bolen, PhD
Updated April 02, 2019
Medically reviewed by a board-certified physician

Definition:

The sphincter of Oddi (SO) is a muscular valve found at the end of the bile and pancreatic ducts where they connect to the duodenum of the small intestine. The SO's main job is to regulate the flow of bile and pancreatic juices into the small intestine. 

These juices are important for the process of digestion. Bile is stored in the gallbladder for the digestion of fat, The pancreas secretes enzymes for the breakdown of protein, carbohydrates as well as fat. The SO is typically closed, but it opens after a meal is eaten to allow these juices into the duodenum. In the duodenum, these juices break down their respective food components so that nutrients can be absorbed into the bloodstream. The SO closes after releasing the juices so as to prevent the contents of the small intestine from backing into the bile and pancreatic ducts.

When the SO is not working properly, a diagnosis of SO dysfunction is considered. SO dysfunction is a functional gastrointestinal disorder in which the SO does not relax and open, resulting in a back-up of bile and pancreatic juices. SO dysfunction appears as episodes of steady pain in the central and right parts of the upper abdomen a short time after eating. SO dysfunction is mostly seen in people who have had their gallbladders removed (cholecystectomy) and people diagnosed with pancreatitis.

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