Understanding Sphincter of Oddi Dysfunction: Symptoms, Diagnosis, and Treatment

The sphincter of Oddi is a muscular valve that opens and closes and allows bile and pancreatic juice to flow into the small intestine. This sphincter normally remains closed, opening only in response to a meal so that digestive juices enter the duodenum (proximal part of the small intestine) and mix with food for digestion. In the sphincter of Oddi dysfunction, the sphincter muscle does not properly open when it should, and this causes a backup of digestive juices and results in severe abdominal pain.

This article will let you know more about the sphincter of Oddi dysfunction, its symptoms, causes, challenges in its diagnosis, and treatment procedures.

Sphincter of Oddi dysfunction is the condition where the sphincter of the Oddi muscle does not open when it should open to allow the flow of digestive juices, and this results in a backup of digestive juices, causing severe pain in the abdomen.

When the sphincter of Oddi functions properly, it opens to allow bile and pancreatic juice to flow through and then closes again. However, in the case of the sphincter of Oddi dysfunction, this sphincter does not open as it should and the digestive juices get trapped behind it, thus causing symptoms of abdominal pain, which is similar to what people experience with gallbladder pain.

People who undergo cholecystectomy (removal of gallbladders) are most likely to develop sphincter of Oddi dysfunction. Thus, Oddi dysfunction is also sometimes called “post-cholecystectomy syndrome”. Among the general population, the prevalence of sphincter of Oddi dysfunction is about 1.5%. However, it is higher amongst those who have undergone cholecystectomy and females between the ages of twenty to fifty years of age.⁽¹⁾

Although the sphincter of Oddi dysfunction is not life-threatening, and it usually does not cause any complications, the pain associated with the condition can interfere with one’s quality of life. Appropriate and timely treatment can provide needed relief and improve overall quality of life.

There are two primary types of Sphincter of Oddi dysfunction. They are:

Type 1: Biliary Dyskinesia: In Bilary dyskinesia, the digestive juices from the bile ducts are unable to drain into the intestine.

Type 2: Pancreatitis: In this type of sphincter of Oddi dysfunction, the backup occurs in the pancreas and results in inflammation.

There are three categories of Sphincter of Oddi dysfunction.

Category I and II: In these two categories, diagnosis would give clear evidence of the dysfunction, such as abnormal blood test results, or a dilated bile or pancreatic duct seen with an ultrasound.

Category III: There are no clear-cut laboratory findings or abnormalities of such a category of dysfunction. The only evidence of the sphincter of Oddi dysfunction is the abdominal pain. It is more difficult to diagnose and treat this category of sphincter dysfunction.

The symptoms of sphincter of Oddi dysfunction usually come and go over time. The severity of this condition can also vary from one occurrence to the next. However, some common symptoms include:

• Pain located in the mid or right upper abdomen.
• Sometimes shoulders and back pain.
• The abdominal pain can be mild, dull, or severe pain.
• Pain in the abdomen can last anywhere from several minutes to several hours.

• Bile juice can leak back into the bloodstream because of the prolonged obstruction in case of sphincter of Oddi dysfunction.
• It can lead to a yellowish discoloration of the skin and eyes.
• Liver function tests might show abnormalities.

Other Symptoms: Some other symptoms of sphincter of Oddi dysfunction could include chills, fever, diarrhea, vomiting, and nausea.

Not a single cause for sphincter of Oddi dysfunction has been identified yet, it appears that some individuals are more at risk of developing the condition than others. This includes those who have had their gallbladders removed. Some research suggests that middle-aged women are at an increased risk for the condition.⁽²⁾ In persons with recurrent idiopathic pancreatitis and chronic pancreatitis, the prevalence of sphincter of Oddi dysfunction could be as high as 72% and 59% respectively.⁽³⁾

Some risk factors for sphincter of Oddi dysfunction include:

• Previous gallbladder surgery.
• Gallbladder pancreatitis
• Previous gastric bypass surgery
• Having gallstones
• Previous gallstone lithotripsy
• Hypothyroidism
• Liver transplant
• Irritable bowel syndrome
• Certain medications, such as opiates
• Alcoholism

Diagnosis of the sphincter of Oddi dysfunction could be quite challenging because locating the sphincter could be quite hard as it could be tightly closed and sit in the folds of the duodenum. However, there are some specific ways to diagnose the conditions.

The sphincter of Oddi dysfunction could be diagnosed in the following ways.

Blood tests are the initial diagnostic tests for the sphincter of Oddi dysfunction. These tests are done to check for higher-than-normal liver or pancreatic enzymes.

Ultrasound is an imaging test that could be done to look at the bile duct, pancreas, or liver. This is another way to diagnose the sphincter of Oddi dysfunction. Magnetic resonance cholangiopancreatography (MRCP) is also an imaging study of bile and pancreatic ducts.

ERCP is a test that measures the sphincter pressure by looking directly inside the duct system while getting X-ray images and taking visual pictures. In this, the doctor passes a flexible endoscope down the throat and into the duodenum to examine the drainage hole of the bile duct.

Locating the sphincter of Oddi is quite difficult, as it might be tightly closed, and sits in the folds of the duodenum. However, once it is located, a dye would be injected into the bile duct and pancreatic duct to double-check for any forms of obstruction including stones.

NOTE: There are risks associated with ERCP; especially the chance of suffering an attack of pancreatitis.

This internal ultrasound is done while examining the upper gastrointestinal tract. Endoscopic ultrasound (EUS) uses an endoscope that is put into the mouth, down into the stomach of the patient, and onto the first part of the small intestine. The EUS gives very detailed images and the test looks for causes of pain, such as chronic pancreatitis.

Treatments for sphincter of Oddi dysfunction include the following.

Nitrates and calcium channel blockers are used to help relieve symptoms of this sphincter dysfunction. These medications can also help in stopping the spasms associated with the sphincter of Oddi dysfunction and should first be used in type III SOD patients, before any invasive therapy.

Botulinum toxin or Botox injection might be used in patients with Sphincter of Oddi dysfunction. It has been shown to reduce the sphincter of Oddi pressure in animals⁽⁴⁾, and subsequently in several case reports in patients with the sphincter of Oddi dysfunction.^{(5, 6)} To ease symptoms, Botulinum toxin injection might be done through an endoscope.

Sphincterotomy is recommended for patients with severe pain due to the sphincter of Oddi dysfunction. This procedure is highly effective and usually safe. During this procedure, the sphincter of the Oddi muscle is surgically cut.

First, the patient is either sedated or put uner anesthesia. Then the gastroenterologist pushes a thin endoscopic instrument through the mouth into the small intestine, where the sphincter of Oddi is located, and then cuts the muscle. The doctor will also check for any gallstones within the bile ducts.

Although sphincterotomy helps provide relief from pain in most cases, the procedure poses a high risk of complications, which include mild inflammation in the pancreas, hemorrhage, and even perforation.

Someone with SOD should follow certain tips that would help them manage the condition. Some of these tips include:

• Avoid smoking and do not drink alcohol.
• Limit high-fat foods.
• Avoid spicy foods, fibrous raw vegetables, and acidic fruits.
• Coffee and other caffeinated beverages should be limited.
• Keep cholesterol level under control.
• Maintain a healthy weight.
• Eat smaller meals quite often

With appropriate treatment and medications, about 70% of patients with sphincter of Oddi dysfunction experience long-term relief, depending on the type of sphincter of Oddi dysfunction. This medical condition does not necessarily reduce one’s life expectance, though it can reduce the quality of their life.

The sphincter of Oddi dysfunction can be quite a challenging health condition. However, with proper treatment, one can come out of this severe medical condition. So, for the best chance of recovery, one should stick to the prescribed treatment plan and also follow the necessary dietary changes.

References: