Sphincter of Oddi: physiology of motor function and clinical application

Abstract

Sphincter of Oddi (SO) regulate bile flow and prevent reflex of duodenal content to pancreato-biliary duct system. SO changes its behavior dramatically. In postprandial state, SO relaxes synchronously with gallbladder contractions, and facilitate bile output. Conversely in fasting state, SO assist gallbladder filling by its basal pressure and phasic contractions. Furthermore, SO allows small volume of bile flow out cyclically into duodenum, then maintain entero-hepatic circulation of bile. Abnormal SO motor function cause SO dysfunction (SOD) and gallstone recurrence. SO manometry is still gold standard for diagnosis of SOD, however, new safer and reliable diagnostic method is desired. Balloon dilatation of SO and laparoscopic explorations of common bile duct are promising treatment for preserving SO motor function. Some problems such as high risk of pancreatitis and technical difficulties should be solved. SO motor physiology is largely elucidated in over 130 years since Rugelo Oddi discovered SO, however, fundamental question such as "pump or resistor issue" is still controversial.