What Is Sphincter of Oddi Dysfunction?

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Your sphincter of Oddi (SO) is something that you would never give a thought to - unless it was acting up. Your SO is a muscular valve that regulates secretions from your gallbladder and your pancreas into your small intestine. When this valve is not working as it should, sphincter of Oddi dysfunction (SOD) is diagnosed.

SOD is a rare health condition. In SOD, the sphincter muscle spasms, causing it to remain shut.

This can result in a backup of bile and pancreatic enzymes into their respective ducts. This backup can also result in swelling of the liver and/or pancreas.

SOD is divided into sub-types:

  • Type I SOD: Presence of pain, an enlarged bile duct, and elevated liver and/or pancreatic enzyme levels.
  • Type II SOD: Presence of pain, with either an enlarged duct or elevated enzyme levels, but not both.
  • Type III SOD: Presence of pain, but no abnormalities are seen via ultrasound or blood work.

Type III SOD may be referred to as functional SOD. This can be further broken down into functional biliary SOD and functional pancreatic SOD.

Risk Factors for SOD

Most cases of SOD occur after gallbladder removal or gastric bypass weight loss surgery. For those cases that occur following gallbladder removal, SOD is more prevalent in women than men, but it is important to note that SOD only affects a very small percentage of people.

Symptoms of SOD

The main symptom of SOD is intermittent pain in the mid- to upper-right part of the abdomen. The pain may spread to the shoulder or across the chest. Pain episodes can be brief or last several hours. Pain levels may vary from episode to episode, and range from relatively mild to incapacitating.

Related symptoms include loss of appetite, nausea, and weight loss. Fever, vomiting and jaundice can also occur. (Remember, serious symptoms such as these require immediate medical attention.)

Diagnosis of SOD

There are various tests for SOD. The goal of diagnostic testing is to obtain an accurate diagnosis as to what might be causing the symptom of abdominal pain. Here are some diagnostic options:

Blood work: This is typically the first test that is done. Your doctor will be looking for elevated liver or pancreas enzymes.

Imaging: Your doctor may want to try to get a picture as to what is going on inside of you, particularly your bile duct, liver and pancreas. This could be done through X-rays, ultrasound, CT scan or MRI.

MRCP: Magnetic resonance cholangio-pancreatography uses dye and magnets to get an image of your bile and pancreatic ducts.

ERCP: Endoscopic retrograde cholangio-pancreatography uses an endoscope, dye and X-rays to examine the bile and pancreatic ducts. ERCP is quite invasive and therefore is only recommended for Type I or II patients.

SO manometry can be done during ERCP to measure the pressure of the sphincter muscles and is considered to offer a definitive diagnosis of SOD.

Treatment of SOD

Treatment of SOD depends on the severity of symptoms. For mild cases, your doctor may prescribe muscle relaxants, antispasmodics and/or other types of pain relievers.

In a severe case, the SO is cut during an ERCP, a procedure known as sphincterotomy. This is done to either remove any stones that might be lurking in the ducts or to improve the ducts' ability to drain. This procedure is done only if SO manometry indicates the presence of high pressure within the SO and is thought to bring about significant pain relief for approximately 50% of patients. However, there are significant risks to this procedure. The most severe is a risk for the development of pancreatitis. Another possible risk is that the procedure may cause scarring and thus a return of symptoms.

Sources:

Behar, J., et.al. "Functional Gallbladder and Sphincter of Oddi Disorders" Gastroenterology 2006 130:1498–1509.

"Sphincter of Oddi Dysfunction" University of Maryland Health Center Accessed July 22, 2105.

"Sphincter of Oddi Dysfunction" University of Rochester Health Encyclopedia Accessed July 22, 2015.

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