What is sphincter of Oddi dysfunction (SOD)?
The sphincter of Oddi is a muscular valve at the end of the common bile duct, which controls the flow of the bile and pancreatic juice into the duodenum.
Sphincter of Oddi dysfunction (SOD) refers to insufficient relaxation or spasm of the sphincter resulting in a build-up of the bile and/or pancreatic juice and subsequently in recurrent upper right abdominal pain or acute pancreatitis .
SOD can occur in individuals with or without the gallbladder. 90% of the affected individuals are women and only 10% are men [11,18,23]. Women between 30 and 50 years are at the highest risk.
You can suspect you have SOD when you have chronic upper abdominal pain in the absence of gallstones or after gallbladder removal and when other more common causes of pain, such as irritable bowel syndrome, peptic ulcer or hepatitis, have been excluded by appropriate investigations.
Causes and Mechanism of SOD
The exact cause of SOD is not known .
Risk factors may include microscopic stones in the bile (microlithiasis) , inflammation of the duodenum , opiate addiction , high progesterone levels (contraceptives, pregnancy) , gallbladder removal surgery  or gastric bypass surgery . In some individuals, SOD may appear as a psychosomatic disorder associated with depression, obsessive compulsive behavior or anxiety, sensitive bowel (visceral hyperalgesia) or irritable bowel syndrome [7,19].
The pain can be triggered by large meals and opiates, such as morphine , and possibly by other narcotics, such as fentanyl , codeine, dilaudid, hydrocodone, meperidine and oxycodone.
There is a wide agreement about the existence of SOD type I and II, but not type III [11,15,19]:
- SOD type I consists of upper abdominal pain, dilation of the bile ducts and elevated liver enzymes.
- SOD type 2 involves upper abdominal pain and either dilation of bile ducts alone or elevated liver enzymes alone.
- SOD type 3 involves only upper abdominal pain without the bile duct dilation or elevated liver enzymes.
The term pancreatic SOD refers to SOD associated with pancreatitis.
Papillary stenosis or narrowing of the papilla Vateri (the opening of the common bile and pancreatic duct into the duodenum) is a condition similar to SOD; it is probably caused by recurrent pancreatitis or passage of gallstones .
Symptoms of SOD according to Rome III criteria [7,13,23,24]:
- Chronic, recurrent upper right (or middle) abdominal pain that:
- lasts at least 30 minutes, initially builds up and then remains constant during the attack
- is severe enough to interrupt your daily activities
- may radiate to the middle back or right shoulder blade
- is recurrent but does not appear every day
- is not relieved by changing the body position, bowel movements, gastric acid-lowering drugs (antacids, H2 blockers, proton pump inhibitors) or antispasmodics
- may be triggered by meals, especially fatty meals, and opiates, like morphine
- It is not clear if nausea, bloating, constipation, diarrhea and unintended weight loss are symptoms of SOD or eventual coexisting disorders, such as irritable bowel syndrome.
A doctor can make a diagnosis of SOD by endoscopic retrograde cholangiopancreatography (ERCP), which can reveal a dilatation of the common bile or pancreatic duct or both. Along with ERCP, a doctor can perform manometry (in SOD type II and SOD III), that is measuring the pressure within the common bile duct at the level of the sphincter. When the pressure exceeds 40 mm Hg, a doctor usually suggests a cut of the sphincter [1,2].
Blood tests can reveal elevated liver and pancreatic enzymes and bilirubin .
Abdominal ultrasonography can reveal a dilatation of the common bile duct.
Chart 1. Differential Diagnosis of Gallbladder Dyskinesia
Chart 1. References: [5,7,13]
There seems to be no specific diet for sphincter of Oddi dysfunction that would work for everyone. You can experiment with foods and see if any of them is causing pain. According to anecdotal reports, foods that can trigger symptoms in irritable bowel syndrome may also trigger pain in biliary dyskinesia:
- Fatty, oily and fried foods (red meat, fast food, cheese and possibly other dairy, chocolate)
- Caffeinated, carbonated and alcoholic beverages
- Sugar (sweets, fruits, sweetened beverages)
- Spicy foods
Note, that having small meals may be more beneficial than sticking to a low-fat diet. A low-FODMAP diet may be beneficial for some individuals. Gluten-free diet can probably help only in individuals with celiac disease.
It can also help if you learn how to cope with stress and maintain regular working, eating and sleeping pattern.
SOD can be treated by endoscopic biliary sphincterotomy (EBS), that is by cutting the sphincter of Oddi. This decreases the pressure within the common bile duct and relieves pain [11,12,14]. A doctor may or may not place a small tube (stent) to keep the bile duct open. The effectiveness of sphincterotomy ranges from 55-95% in biliary SOD type I, 70% in type II, and 8-65% in type III [1,4,15,17]. 75-88% of the individuals with pancreatic SOD may benefit from sphincterotomy [15,17]. Individuals with normal pressure (<40 mm Hg) in the bile duct will much less likely benefit from sphincterotomy .
There is INSUFFICIENT EVIDENCE about the long-term effectiveness of the following therapies in relieving pain in SOD [10,18,19]:
- Antibiotics (erythromycin) 
- Antidepressants (amitriptyline)
- Antispasmodic drugs (hyoscyamine, trimebutine )
- Botulinum toxin injection 
- Calcium channel blockers (nicardipine, nifedipine) 
- Digestive enzymes
- Glucagon [8,9]
- Magnesium supplements
- Nitrates (nitroglycerin) 
- Transcutaneous electrical nerve stimulation (TENS)
NOTE: Narcotics may worsen the pain .
There seems to be NO EVIDENCE about the effectiveness of “liver flush,” herbs and other home remedies in relieving pain in SOD.
Acute pancreatitis can occur as a complication of SOD, endoscopic retrograde cholangiopancreatography (ERCP) sphincterotomy or endoscopic biliary sphincterotomy (EBS) . It causes sudden upper middle or left abdominal pain, nausea and vomiting.
- If you have the diagnosis of “sphincter of Oddi dysfunction (SOD) type I” (pain + dilated common bile duct + elevated liver enzymes), you will much more likely benefit from surgical (endoscopic) treatment than when your bile duct and/or liver enzymes are normal (SOD type II or III).
- When you have the diagnosis “suspected” or “possible SOD,” consider diet (small meal portions, avoiding FODMAPs) and life style changes (exercise, coping with stress) rather than surgery.
- When you have the diagnosis of “SOD stenosis,” or “papillary stenosis,” which means your sphincter of Oddi is physically narrowed, surgery is probably the only effective treatment.
- Check for other causes of right upper abdominal pain after gallbladder removal.
- George J et al, 2009, Gallbladder and biliary dyskinesia PubMed
- Craig A et al, 2001, Still awaiting evidence for sphincterotomy for biliary sphincter of Oddi dysfunction Cochrane
- Tierney S et al, 1999, Progesterone alters biliary flow dynamics PubMed Central
- Tooli J, 2002, Biliary dyskinesia PubMed
- Zakko SF et al, 2016, Functional gallbladder disorder in adults UpToDate
- 2013, Type 1 Sphincter of Oddi Dysfunction due to Chronic Opium Addiction ResearchGate
- Bistritz L et al, Sphincter of Oddi dysfunction: Managing the patient with chronic biliary pain PubMed Central
- Ballal MA et al, 2000, Physiology of the Sphincter of Oddi – the present and the future? – part 1 The Saudi Journal of Gastroenterology
- Biliotti D et al, 1989, Effect of glucagon on sphincter of Oddi motor activity PubMed
- Sphincter of Oddi dysfunction International Foundation for Functional Gastrointestinal Disorders
- Romagnuolo J et al, 2014, Recent Research on Sphincter of Oddi Dysfunction PubMed Central
- Cotton PB et al, 2014, Effect of endoscopic sphincterotomy for suspected sphincter of Oddi dysfunction on pain-related disability following cholecystectomy: the EPISOD randomized clinical trial PubMed
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- Seetharam P et al, 2008, Sphincter of Oddi and its Dysfunction PubMed Central
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- McCammon RL et al, 1983, Reversal of fentanyl induced spasm of the sphincter of Oddi PubMed
- Sgouros SN et al, 2006, Systematic review: sphincter of Oddi dysfunction–non-invasive diagnostic methods and long-term outcome after endoscopic sphincterotomy PubMed
- Fogel EL et al, Sphincter of Oddi dysfunction GastroHep
- Wilcox CM et al, 2015, Sphincter of Oddi dysfunction Type III: New studies suggest new approaches are needed PubMed Central
- FAQs about sphincter of Oddi dysfunction John Hopkins Medicine
- Sherman S et al 2001, Sphincter of Oddi Dysfunction: Diagnosis and Treatment Journal of the Pancreas
- Vitton V et al, 2012, Medical treatment for sphincter of Oddi dysfunction: Can it replace endoscopic sphincterotomy? PubMed Central
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- Rome II diagnostic criteria for functional gastrointestinal disorders Romecriteria.org
- Sphincter of Oddi dysfunction Cleveland Clinic