What is the sphincter of Oddi?
The sphincter of Oddi is a muscular valve that consists of 2 parts: the biliary sphincter at the end of the common bile duct and the pancreatic sphincter at the end of the pancreatic duct. It controls the flow of the bile and pancreatic juice into the duodenum.
What is sphincter of Oddi dysfunction (SOD)?
Sphincter of Oddi dysfunction (SOD) refers to insufficient relaxation (spasm) of the sphincter, which results in a back up of the bile and/or pancreatic juice and thus in recurrent upper right abdominal pain or acute pancreatitis . Either–the biliary or pancreatic–or both parts of the sphincter can be affected.
SOD can occur in individuals with or without the gallbladder and is much more common in women (90%), especially in the middle-aged (30-50 years) ones, than in men (10%) [11,18,23].
You can suspect you have SOD when you have chronic upper abdominal pain in the absence of gallstones or even in the absence of gallbladder and when other more common causes of pain, such as irritable bowel syndrome or hepatitis, have been excluded.
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)  and 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 (IBS) [7,19].
The pain can be triggered by large meals and opiates, such as morphine , and possibly other narcotics, such as fentanyl , codeine, dilaudid, hydrocodone, meperidine and oxycodone.
Biliary dyskinesia and spasm of sphincter of Oddi (improper relaxation of sphincter of Oddi) may be involved.
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 bile duct dilation or elevated liver enzymes.
Papillary stenosis or narrowing of the papilla Vateri–the opening of the common bile and pancreatic duct into the duodenum–, is considered another type of SOD caused by repetitive passing of gallstones or by pancreatitis .
Symptoms of SOD according to Rome III criteria [7,13,23,24]:
- Chronic, recurrent upper right (or upper 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 postural change, 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 (IBS).
A doctor can make a diagnosis of SOD by endoscopic retrograde cholangiopancreatography (ERCP), which can reveal dilated common bile or pancreatic duct or both. Along with ERCP, a doctor can perform manometry (in SOD 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 (see below) [1,2].
Blood tests. Liver and pancreatic enzymes and bilirubin are often elevated in SOD .
Abdominal ultrasonography can reveal a dilated common bile duct.
Chart 1. Differential Diagnosis of Gallbladder Dyskinesia
Chart 1. References: [5,7,13]
It seems, there is no exact diet for sphincter of Oddi dysfunction that would work for everyone. Try to find out which foods trigger pain and eliminate them from the diet. 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 meal portions 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.
Learning how to cope with stress and maintaining regular working, eating and sleeping pattern can also help.
SOD can be treated by endoscopic biliary sphincterotomy (EBS), that is by a cut (incision) of the sphincter of Oddi that results in a decrease of pressure within the bile duct and thus in pain relief [11,12,14]. A doctor may or may 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 . 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.
- 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
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- Ballal MA et al, 2000, Physiology of the Sphincter of Oddi – the present and the future? – part 1 The Saudi Journal of Gastroenterology
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- Sphincter of Oddi dysfunction International Foundation for Functional Gastrointestinal Disorders
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- 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
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- Rome II diagnostic criteria for functional gastrointestinal disorders Romecriteria.org