What is Sphincter of Oddi Dysfunction?
The sphincter of Oddi has three major functions: 1) regulation of bile and pancreatic flow into the duodenum, 2) diversion of hepatic bile into the gallbladder, and 3) the prevention of reflux of duodenal contents into the pancreaticobiliary tract. With the ingestion of a meal, the gallbladder contracts and there is a simultaneous decrease in the resistance in the sphincter of Oddi zone. The sphincter of Oddi consists of circular and longitudinal smooth muscle fibers surrounding a variable length of the distal bile and pancreatic duct. There are three discrete areas of muscle thickness, or mini sphincters: the sphincter papillae, the sphincter pancreaticus, and the sphincter choledochus (Figure 2).  | | Figure 2. Mini sphincters, or discrete areas of muscle, comprise the sphincter of Oddi. |
The major physiologic role of the sphincter is the regulation of the flow of bile and pancreatic juice. Cholecystokinin (CCK) and nitrates decrease the resistance offered by the sphincter. Laboratory studies observing the effects of numerous peptides, hormones, and medications on the sphincter have suggested a multifactor control mechanism for the sphincter of Oddi. There are two types of sphincter of Oddi dysfunction: 1) papillary stenosis and 2) sphincter of Oddi dyskinesia. Papillary stenosis is a fixed anatomic narrowing of the sphincter, often due to fibrosis. Sphincter of Oddi dyskinesia refers to a variety of manometric abnormalities of the sphincter of Oddi.
Symptoms
The major presenting symptom in patients with sphincter of Oddi dysfunction is abdominal pain. The pain is characteristically sharp, postprandial, and located in the right upper quadrant or epigastrium. The pain may be associated with nausea and/or vomiting, may last for several hours, and may radiate to the back or shoulder blades. Fever, chills, and jaundice are uncommon symptoms. Patients may also present with acute recurrent pancreatitis.
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