Sphincter of Oddi Disfunction

There are many different sphincters throughout the body. The sphincter of Oddi - named for the Italian physician who discovered it - is a complex muscular valve that allows digestive fluids from the liver and pancreas to flow into the first loop of the small intestine (duodenum). The sphincter, which surrounds the common bile and pancreatic ducts, is normally closed, opening only in response to a meal so that digestive juices can enter the small intestine and mix with the food for digestion.

Sphincter of Oddi dysfunction (SOD) refers to a spasm of the sphincter muscle that causes a backup of those digestive fluids - bile from the liver and enzymes from the pancreas - that are supposed to flow to the small intestine. The backup soon may cause abdominal pain, while more prolonged obstruction can cause bile to leak into the bloodstream, and cause the obstruction of juices exiting the pancreas, which can lead to pancreatitis.

Mild forms of SOD can be managed by anti-spasm medicines. For more severe cases, the sphincter muscle may be cut to facilitate drainage of the pancreatic duct. MUSC has developed a rare expertise in treating SOD safely and effectively.

To help diagnose SOD, a physician may use a flexible tube called an endoscope to explore and collect images of the digestive track, including the bile and pancreatic ducts, to rule out stones or other obstructions as a cause of the backup. While endoscopic ultrasound (EUS) may be used, the physician is more likely to use another variation called endoscopic retrograde cholangiopancreatography (ERCP). During the ERCP procedure, the physician may also measure the sphincter's squeeze pressure with sphincter of Oddi manometry (SOM) - MUSC is world renowned for expertise in this field.

If the pressure is especially high, the sphincter may be cut during the ERCP procedure (sphincterectomy) to provide relief. However, sphincterectomy also can cause bleeding, perforation, scarring and potentially pancreatitis. Surgery may be considered as an alternative way to open up the sphincter of Oddi (sphincteroplasty) and may be one of the only options if endoscopic sphincterectomy does not work in the long or short term.

SOD should be approached and managed with considerable care. Patients can expect better results from a specialty center such as MUSC, where investigators from MUSC currently are involved in a National Institutes of Health study (EPISOD) designed to improve treatment of SOD patients.

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