Sphincter of Oddi Dysfunction

Abstract

Sphincter of Oddi dysfunction (SOD) refers to structural alterations (stenosis) or functional abnormalities (dyskinesia) of the sphincter of Oddi that can impede biliary and pancreatic duct flow, causing recurrent upper abdominal pain with or without abnormalities of liver or pancreatic chemistries or dilated duct. SOD is divided into two clinical entities, biliary SOD and pancreatic SOD. Typically, patients with SOD have symptoms such as recurrent attacks of the epigastrium and/or right upper quadrant pain or idiopathic recurrent acute pancreatitis. The diagnosis may be supported by hepatobiliary scintigraphy or provocation tests such as secretin MRCP but definitive diagnosis requires sphincter of Oddi manometry (SOM). Patients with type I biliary SOD who have biliary-type pain, abnormal liver tests, and a dilated common bile duct are referred for endoscopic sphincterotomy (EST) without manometry. Patients with type II biliary SOD who have biliary-type pain and either abnormal liver tests or a dilated common bile duct are referred for SOM and that an EST be performed if there is evidence of sphincter of Oddi stenosis. Patients with type III biliary SOD who have only biliary-type pain should avoid undergo ERCP and EST due to higher risk of complications and no benefit from EST. Patients with pancreatic SOD present with recurrent episodes of pancreatitis and have a negative evaluation for alternate causes. Patients who have suspected pancreatic SOD will typically require SOM and that those with elevated sphincter pressures undergo EST.