What causes bile duct obstruction?
This article explores some of the leading causes of bile duct obstruction, its symptoms, diagnosis, and treatment.
What is a bile duct obstruction?
If untreated, a blockage of the bile ducts can cause severe infection.
The liver produces a liquid called bile. Bile contains cholesterol and bile salts that help the gut to digest fats. It also contains a waste product called bilirubin.
Bile passes through the bile ducts from the liver to the gallbladder, which stores it. It travels to the small intestine when it is needed to help digest food. This network of ducts is part of the biliary system.
When one or more of the ducts that transport bile become blocked, it is known as a bile duct obstruction. It is also commonly referred to as biliary obstruction.
A bile duct obstruction can lead to bile accumulating in the liver and a buildup of bilirubin in the blood.
Some of the most common causes of bile duct obstruction include:
Gallstones are a common cause of bile duct obstruction. They can form when there is a chemical imbalance in the gallbladder. If they are large enough, they may block a bile duct as they pass through the biliary system.
Bile duct or pancreatic cancer
Bile duct cancer refers to all cancers that develop within the biliary system. The resulting tumors may block a bile duct.
Cancers that have started elsewhere in the body may also spread to the biliary system where they can cause an obstruction.
A blockage can sometimes result from an injury that occurs during a medical procedure, such as gallbladder surgery or endoscopy.
Choledochal cysts can sometimes cause bile duct obstructions. These cysts, which are sections of an enlarged bile duct, are congenital, meaning some people are born with them. They are also rare.
A history of any of the following can increase the risk of bile duct obstruction:
- pancreatic cancer
- chronic pancreatitis
- recent biliary surgery
- recent biliary cancer
- abdominal trauma or injury
- taking immunosuppressant medications, as some can result in infections that block the bile duct
Nausea and vomiting can be symptoms of bile duct obstruction.
Symptoms of a blocked bile duct may come on suddenly, or a person may start to notice them slowly over many years.
Some of the symptoms are related to the obstruction, causing liver products to back up and leak into the bloodstream. Others are caused by the bile duct not being able to deliver the digestive juices that the gut needs. This can stop the body from absorbing some fats and vitamins properly.
When bilirubin is unable to enter the bile, it builds up in the body and can cause jaundice. This is when a person's skin and the whites of their eyes turn yellow. The lack of bilirubin in the bile can also cause dark urine and pale stools
People with bile duct obstruction also often experience:
- abdominal pain, usually in the upper right side
- fever or night sweats
- nausea and vomiting
- tiredness or lack of energy
- unintentional weight loss
- loss of appetite
The first step in diagnosis is a physical examination, during which a doctor will try to feel the person's gallbladder. Liver damage can cause similar symptoms to biliary obstruction, so the doctor may also ask about alcohol or drug use as well as sexual practices.
A doctor may also carry out blood tests. The following results would suggest a biliary obstruction:
- higher than usual levels of bilirubin
- higher than usual levels of alkaline phosphatase
- higher than usual levels of liver enzymes
If blood tests suggest a biliary obstruction, the doctor may recommend one of the following imaging methods to confirm the diagnosis:
- abdominal ultrasound
- abdominal computed tomography (CT) scan
- magnetic resonance cholangiopancreatography (MRCP)
- percutaneous transhepatic cholangiogram (PTCA)
- endoscopic retrograde cholangiopancreatography (ERCP)
Treatment aims to relieve the blockage and depends on the underlying cause.
Doctors can usually remove gallstones using an endoscope during an ERCP. However, some people may still require surgery.
Someone with severe or frequent symptoms may need to have their gallbladder removed. This will stop the problem of gallstones reoccurring. People can lead healthy lives without a gallbladder.
If the cause is found to be cancer, the ducts may need to be stretched and drained. Doctors will do this either using an endoscope or by placing a needle through the skin. They will then treat the cancer with a mix of chemotherapy and radiotherapy, depending on its type, size, and location.
If someone has choledochal cysts, a doctor will usually recommend a surgical procedure to correct the enlarged areas of bile ducts.
If left untreated, bile duct obstructions can lead to life-threatening infections. In the long-term, they can also result in chronic liver diseases, such as biliary cirrhosis.
If the "drainpipe" at the bottom of the liver, or the common bile duct, remains blocked, a buildup of bilirubin in the bloodstream can lead to jaundice.
This blockage can also lead to bacteria backing up into the liver, which can cause a severe infection known as ascending cholangitis.
If the blockage occurs between the gallbladder and the common bile duct, a person is at risk of cholecystitis. This is an inflammation of the gallbladder that can lead to a severe infection or the rupturing of the gallbladder. Both of these complications of cholecystitis require emergency surgery to remove the gallbladder.
Research has suggested a link between obesity and gallstones.
Researchers have found links between gallstones and obesity. Some experts believe that consuming less cholesterol, saturated fats, trans fats, and refined sugar reduces the risk of gallstones developing.
While other causes of bile duct obstructions are not usually preventable, being aware of the risk factors and symptoms means that people can seek medical assistance as soon as they realize there may be a problem.
Anyone with one or more of the risk factors for bile duct obstruction should see a doctor if they experience:
- lighter-colored stools
- darker-colored urine
- yellowing of the skin