What Causes a Dilated Bile Duct?

A.M. Boyle

The bile ducts are tubes that transport bile from a person’s liver to the gallbladder and small intestine. A dilated bile duct, or one that is enlarged, typically occurs when there is an obstruction blocking the flow of bile. When the bile cannot pass through a particular duct, it builds up, and the structure becomes distended. Most commonly, the obstruction is caused by a gallstone, but cysts or tumors are also possible. Surgical trauma and inflammation can also cause dilation.

Liver anatomy, including the bile duct.
Liver anatomy, including the bile duct.

The gallbladder stores bile produced by the liver. Sometimes, if the bile contains too much cholesterol, bile salts or bilirubin, pebble-like substances called gallstones can form. Gallstones can be as small as a grain of sand or as big as a golf ball. They can travel from the gallbladder into the bile ducts. If the stone is large enough, it can become lodged there, blocking the flow of bile and causing a dilated bile duct.

Surgical trauma can also cause a dilated bile duct.
Surgical trauma can also cause a dilated bile duct.

Cysts are fluid-filled masses of tissue that can occur in various places in the body. On occasion, a cyst can form in a bile duct, most often in the common bile duct. Depending upon the size and location of a cyst, it could impede the flow of bile.

A gallstone can become lodged in the bile ducts, blowing the flow of bile and causing a dilated bile duct.
A gallstone can become lodged in the bile ducts, blowing the flow of bile and causing a dilated bile duct.

When a tumor occurs in the bile duct, it is called a cholangiocarcinoma. Whether the tumor is benign or malignant, it can block the bile duct. As with a cyst or a gallstone, if the tumor is large enough to cause a complete obstruction, the bile will not be able to travel through the duct. This, in turn, will cause the bile duct to become dilated.

Gallstones, which are hardened deposits of bile, are often a cause of blocked bile ducts.
Gallstones, which are hardened deposits of bile, are often a cause of blocked bile ducts.

Surgical trauma can also cause a dilated bile duct. When a person experiences a cholecystectomy or other surgery in that area, the bile ducts can have residual inflammation. As a result of the surgery, the ducts might become swollen and enlarged to some degree. Typically, the distention that results from surgical trauma is expected and is not significant enough to cause serious issues such as a blocked bile duct. On occasion, though, inflammation and distention caused by surgical trauma can create complications warranting further attention.

An ultrasound may be used to investigate gallstones.
An ultrasound may be used to investigate gallstones.

A person experiencing symptoms of a dilated bile duct, such as pain, nausea, jaundice, and fever, should promptly seek medical attention. The cause of a distended duct can usually be determined through an ultrasonogram, computerized tomographic (CT) scan, or a magnetic resonance cholangio-pancreatography (MRCP). Another type of test, called an endoscopic retrograde cholangio-pancreatiogram (ERCP) can often be used not only to diagnose the cause of the dilation but to repair it as well.

Consuming peanuts on a regular basis may help prevent gallstones, which may block bile ducts.
Consuming peanuts on a regular basis may help prevent gallstones, which may block bile ducts.

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Discussion Comments


@ anon939983 - I don't know what date you posted this, but hopefully you will return to see my reply. I am a retired nurse and hopefully you have been able to find a doctor that can give you answers to the pain your Mother is in. Can I assume, you meant "bile" duct enlargement, instead of pile?

If your Mom is having left side pain, why would the doctors say she has bile duct enlargement? The bile ducts, coming from the liver, gallbladder, etc. are all on the right side of the upper abdomen. If she was having problems, due to bile duct dilatation, then her pain should be under the right rib cage and often the pain extends into the mid back region. The reason I say this, is I do have both intrahepatic and extrahepatic bile duct dilatation and am undergoing tests to see the cause for it. I am scheduled to have a consult next month with a gastroenterologist and then an ERCP.

If your Mom is having severe left side pain, I would look at other reasons for the pain. There can be many causes for her to be having left abdominal pain, including heart, bowel, spleen, the end part of the pancreas, part of the stomach, the left part of the liver, left kidney, left adrenal gland, a portion of her ureter, part of the left lung, ribs on the left side, aorta and muscles. Any problems with any of these organs/bones/muscles could directly cause upper left abdominal pain.

The most common causes of left, upper abdominal pain are acute pancreatitis, enlargement of spleen (which can be due to several reasons, such as viral, bacterial or parasitic infections, leukemia and cirrhosis of liver). However if she had cirrhosis, you should notice yellow skin or eyes.

Other reasons for the pain could be due to gastroenteritis, kidney infection, pneumonia, polycystic kidney disease, food poisoning and even excessive gas.

Does she have any other symptoms, such as diarrhea, constipation (other than when she was on morphine drip), elevated temp, loss of appetite, etc.

Common symptoms other than abdominal pain include, nausea, vomiting, dehydration, diarrhea and a loss of appetite. Irritable Bowel Syndrome, or IBS, affects the lower intestinal tract and causes extreme bowel discomfort. It can be characterized by extreme cases of diarrhea or constipation and affects people of all ages, with the most common group being adolescent women.

If you haven't done so, I would schedule an appointment with a gastroenterologist. You can use several websites to check out the doctors before scheduling an appointment. Most of the websites will allow patients to give reviews of the doctor. I do this myself, before seeing any doctor, because believe it or not, even as a former nurse, I have had my fair share of lackadaisical physicians. I personally use websites to check what other patients say about a doctor before making an appointment.


My mom went to hospital with severe pain in her left side. They did some tests and said she had pile duct enlargement. All they did for three days was dope her up with morphine. She is almost 82 years of age and has a lot of health problems.

She does not have a gall bladder anymore and they said she did not have gall stones in the duct. She has had pancreatitis before and many years ago, she had a stint put in for six weeks. On top of this, she is diabetic, she has a bad heart, failing kidneys and severe osteoarthritis. She is on a lot of meds.

The staff at the hospital are very, very negligent and they were bringing my mom meals without checking her chart. They just put her in a room and kept the morphine coming. Her family doctor discharged her. When I heard this from her, I spoke to him and told him that she could not go home under any circumstances. He did not re-admit her and the nurse told her to go home.

My husband and I picked her up and she could barely walk and still cannot walk without severe pain. The doctor also told me she was very constipated and never gave her any laxative and or stool softener while she was on the morphine drip for three days. No home care person was in to see her. The doctor never gave her any antibiotics for her bile enlargement. She is still in a lot of pain.

Family and friends go to her home to fix her light meals. The doctor never told her what to do or if it was a pain caused by her pancreas, how it came on so suddenly or any treatment. This is a joke. How could a doctor release a person with so much pain and not do anything. I would like some answers, she will not go back to the hospital, because she said they won’t do anything. How can the pain go away if she was not given any antibiotics?

This whole situation is just ridiculous. I spoke to my sister and the doctor is not going to get away with not treating my mom.

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