Sphincter of Oddi dysfunction
What is sphincter of Oddi dysfunction?
Digestion, through which the body transforms the food we eat into the energy we need, is a complex process. The liver, the pancreas, and the sphincter of Oddi all play important roles.
The liver provides a chemical called bile to the digestive process, and the pancreas provides pancreatic juice. These chemicals flow into the small intestine to help with digestion. The flow of these chemicals is controlled by a muscle called the sphincter of Oddi.
A sphincter is a muscle (usually round) that can open and close. When it's working properly, the sphincter of Oddi opens to allow bile and pancreatic juice to flow through, and then closes again. However, in a condition called sphincter of Oddi dysfunction, the sphincter muscle does not open when it should. This prevents the bile and pancreatic juice from flowing through, and causes a backup of digestive juices. The backup can cause severe pain in the abdomen.
There are two basic types of sphincter of Oddi dysfunction:
- Biliary dysfunction (the digestive juices are backing up in the bile ducts from the liver);
- Pancreatitis (the backup is occurring in the pancreas, and the pancreas is becoming inflamed).
There are also three categories of sphincter of Oddi dysfunction:
- In categories I and II, doctors can find clear evidence of the dysfunction, such as abnormal blood test results or, with an ultrasound, a dilated (widened) bile duct.
- In category III dysfunction, there are no clear-cut lab findings or abnormalities, and the only evidence of the dysfunction is the abdominal pain. Type III dysfunction is much more difficult to diagnose. Recent studies suggest that these symptoms may not be due to sphincter of Oddi spasm, and that they do not respond to treatment with endoscopic retrograde cholangiopancreatography (ERCP) and sphincterotomy.
Who is at risk for developing sphincter of Oddi dysfunction?
People who have had their gallbladders removed are most likely to develop sphincter of Oddi dysfunction. The procedure to remove the gallbladder is called cholecystectomy, and sphincter of Oddi dysfunction is often referred to as "post-cholecystectomy syndrome." Middle-aged women also appear to be at increased risk for the condition, although doctors aren't sure why.
Symptoms and Causes
What are the symptoms of sphincter of Oddi dysfunction?
The symptoms of sphincter of Oddi dysfunction include:
These symptoms can come and go, and can be mild one time and severe the next.
Diagnosis and Tests
How is sphincter of Oddi dysfunction diagnosed?
When sphincter of Oddi dysfunction is suspected, your doctor will first check to see if the abdominal pain is caused by another condition. It is important to make sure patients with abdominal pain don't have serious conditions such as cancer of the pancreas or bile ducts, peptic ulcer disease, or stones in the ducts that carry the bile from the liver. In some cases, even heart conditions such as angina (chest pain) or ischemia (the heart doesn’t get enough blood) can cause pain that seems to be coming from the abdomen.
Your doctor may want to examine the sphincter of Oddi to see if it is functioning normally. This is done with a procedure called sphincter of Oddi manometry, in which the doctor places a small plastic tube into the pancreas duct or bile duct near the sphincter of Oddi to measure how well it is contracting and expanding. Patients are placed under sedation for this procedure.
Management and Treatment
How is sphincter of Oddi dysfunction treated?
If the pain is not too severe, especially in hard-to-diagnose category III patients, medical treatment is usually the first course of action. Some patients can get relief by using pain medications that prevent the sphincter of Oddi from having spasms.
When the pain is severe, and tests have clearly identified the pain as being caused by sphincter of Oddi dysfunction, your doctor may refer you for an endoscopic procedure called a sphincterotomy. You will either be sedated or put to sleep under anesthesia for this procedure. A surgeon will pass a thin instrument into the area of the small intestine where the sphincter of Oddi is located and cut the muscle. The surgeon will also make sure that there aren't any stones in the gallbladder (if it hasn't already been removed) or in the bile ducts.
In most cases, sphincterotomy can bring about good relief of the pain and other symptoms of sphincter of Oddi dysfunction. However, this procedure is usually tried only after medical treatment has failed. Sphincterotomy is a difficult procedure that has a fairly high risk of complications. About 5% to 15% of patients have complications such as mild inflammation of the pancreas, but in some cases the complications are severe and can require a long stay in the hospital.