Sphincter of Oddi dysfunction

Crittenden JP, Dattilo JB. Sphincter of Oddi Dysfunction. 2021 Feb 23. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–.

The patient’s presentation, in combination with the results of their examination, should be used to stratify them to into three classes of sphincter of Oddi dysfunction. Specific diagnostic criteria for SOD include:

  • Transaminitis (greater 2 times the upper limit of normal on 2 or more occasions)
  • Common bile duct dilation (greater than 10 mm on US; greater than 12 mm on ERCP)
  • Biliary pain

Utilizing these criteria, patients are classified as follows:

Type I SOD: all three
Type II SOD: biliary pain and one of the other two criteria.
Type III SOD: biliary pain only [3]

The results of this classification will impact the subsequent treatment plan.

Sphincter of Oddi Dysfunction, gallbladder, common bile duct, main pancreatic duct, accessory pancreatic duct, mini papilla, major papilla, Ampulla of Vater, main pancreatic duct. StatPearls Publishing Illustration

“Invasive interventions for the treatment of SOD include ERCP with sphincterotomy. This modality has been shown to be highly effective and generally safe for patients with SOD, with reports of 90% and 70% resolution of symptoms in types I and II SOD, respectively.[1] Intrasphincteric botulinum toxin injections have been shown to reduce sphincter tone by approximately 50%, but unfortunately, did not resolve patient symptoms in a small case series.[8] However, botulinum toxin and stent placement both have been suggested as possible interim steps to clarify whether or not sphincter relaxation/stenting resolves symptoms, thereby providing a means to predict patient response to a more definitive sphincterotomy.

Patients with type I and type II sphincter of Oddi dysfunction should be referred for management with ERCP and sphincterotomy. Type III SOD has been shown in a trial not to respond to procedural intervention.[9] These patients should instead be referred for medical management, including pain control, as discussed above.”


Small AJ, Kozarek RA. Sphincter of Oddi Dysfunction. Gastrointest Endosc Clin N Am. 2015 Oct;25(4):749-63.

Fig. 1 SO anatomy. ( From Elmunzer BJ, Elta GH. Biliary tract motor function and dysfunction.
In: Feldman M, Friedman LS, Brandt LJ, editors. Sleisenger and Fordtran’s gastrointestinal and liver disease: pathophysiology/diagnosis/management. 9th edition. (PA): Saunders Elsevier; 2010. p. 1068; with permission.)

Key points:

  • Sphincter of Oddi dysfunction (SOD) is a benign, acalculous disease that can result in biliary or pancreatic obstructive symptoms.
  • Chronic, unrelenting epigastric or right upper quadrant pain is not caused by SOD.
  • It is difficult, if not impossible, to diagnose SOD in patients with an intact gallbladder.
  • Modified Milwaukee classification is the most relevant classification system in clinical practice.
  • The classification and response to sphincterotomy of biliary SOD I to III has been defined by randomized controlled trials, whereas pancreatic SOD classification has not.
  • Initial evaluation starts with history taking, biochemistries, and noninvasive imaging before proceeding with endoscopic retrograde cholangiopancreatography (ERCP) and sphincter of Oddi manometry, if necessary.
  • Response to sphincterotomy depends largely on the type of disease, with excellent response to type I and variable results with type II.
  • •Recent level I evidence suggests no role for therapeutic ERCP for type III SOD, which has no better response to treatment than a sham sphincterotomy.

Bistritz L, Bain VG. Sphincter of Oddi dysfunction: managing the patient with chronic biliary pain. World J Gastroenterol. 2006 Jun 28;12(24):3793-802.

“Sphincter of Oddi dysfunction (SOD) is a syndrome of chronic biliary pain or recurrent pancreatitis due to functional obstruction of pancreaticobiliary flow at the level of the sphincter of Oddi. The Milwaukee classification stratifies patients according to their clinical

picture based on elevated liver enzymes, dilated common bile duct and presence of abdominal pain. Type I patients have pain as well as abnormal liver enzymes and a dilated common bile duct. Type II SOD consists of pain and only one objective finding, and Type III consists of biliary pain only. This classification is useful to guide diagnosis and management of sphincter of Oddi dysfunction. The current gold standard for diagnosis is manometry to detect elevated sphincter pressure, which correlates with outcome to sphincterotomy. However, manometry is not widely available and is an invasive procedure with a risk of pancreatitis. Non-invasive testing methods, including fatty meal ultrasonography and scintigraphy, have shown limited correlation with manometric findings but may be useful in predicting outcome to sphincterotomy. Endoscopic injection of botulinum toxin appears to predict subsequent outcome to sphincterotomy, and could be useful in selection of patients for therapy, especially in the setting where manometry is unavailable.”


More PubMed results on management of SOD.

See also: Gallbladder and Bile Ducts: Sphincter of Oddi Dysfunction, Geenen’s Classification, and Sphincter of Oddi Manometry. In: Netter Collection of Medical Illustrations: The Digestive System: Part III—Liver, Biliary Tract, and Pancreas., 2nd ed. (2017).

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