Patient Education Material

What is a Choledochal Cyst?

A choledochal cyst is a swelling/widening or dilatation of the bile ducts. The condition usually affects the part of the bile ducts outside the liver (the common bile duct and the hepatic ducts) but sometimes it also affects those inside the liver (the intrahepatic ducts). The exact cause of a choledochal cyst remains unknown but there are a few theories. One explanation that it happens due to the bile duct not forming properly when the baby is developing in the womb in early pregnancy. This concept supported by the fact that in some cases, the cyst first seen during a routine ante-natal ultrasound scan of the baby in early pregnancy. Another theory that the junction of the bile duct with the pancreatic duct is not normal and forms an abnormally long ‘common channel’. Currently, their arguments in support of both of these.

Yes, it is rare. It affects about 1 in 50,000 children in the West but it occurs more frequently in Oriental and Asian races. Choledochal cysts are three times as common in girls as boys and rarely run in families.

Choledochal Cyst:

There are several types of choledochal cyst. Their positions and sizes may differ. Type I cysts the most common. The ducts inside the liver look normal but the common bile duct may swollen up like a small balloon.

cystic dilatations of biliary tree todani classification


In these types of choledochal cyst, the lower end of the common bile duct often joins up with the pancreatic duct. This is not normal and forms an abnormally long ‘common channel’. This causes the pancreatic juice and the bile to mix together very easily before they enter the duodenum. This early mixing can result in the weakening of the bile duct wall leading to ballooning. In addition, it can lead to complications such as pancreatitis (inflammation of the pancreas) or cholangitis (inflammation of the biliary system). Other types of choledochal cysts less common.

Other types of Choledochal Cysts:

Type II Type III

Type IVa Type V

Apart from these types of choledochal cyst there another known as the “forme fruste” type of choledochal anomaly. Although this involves an abnormality of the junction between the bile duct and pancreatic duct there no widening (dilation) of the ducts. This kind of abnormality can also give rise to serious complications.

Most choledochal cysts are detected in childhood. Some of these cysts found before birth on the antenatal scan. Sometimes, a choledochal cyst found when a child having an abdominal ultrasound scan for an unconnected reason like pain in the abdomen. In some cases, the child symptoms such as

Jaundice (yellowness of eyes):

This is due to the blockage of bile drainage. This might prolonged jaundice (lasting more than two weeks) in a newborn baby or intermittent jaundice (jaundice which comes and goes) in an older infant or child. Usually, jaundice associated with pale-colored stools and dark urine.  § Intermittent abdominal pain (abdominal pain which comes and goes) can severe.


an infection of the bile duct causing fever, jaundice, and sometimes shaking attacks called rigors.


a severe inflammation within the abdomen if the cyst bursts or leaks.

A mass in the abdomen,

Pancreatitis (inflammation of the pancreas)

Diagnosis of Choledochal Cyst:

The diagnosis generally made using a combination of the following:


A physical exam of the child

Tests including blood tests and an ultrasound scan

A choledochal cyst most often suspected if an abdominal ultrasound scan shows a dilated bile duct in a baby or child with jaundice or if the child abdominal pain. Once suspected some other tests required to get more information.

For example, there any blockage in the duct by a stone or there an abnormal junction of the bile duct with pancreatic duct (a long common channel)? These extra tests carried out to get more information about the type of choledochal cyst present which helps the surgeon to get a ‘road map’ to plan the operation. These tests may include:

A detailed ultrasound scan to look not only at the bile ducts but also to look at the blood vessels going to the liver which run alongside the bile ducts.

MRCP (Magnetic Resonance Cholangio-Pancreatography)

This type of detailed scan is carried out in a large machine. It not require X-rays but the patient does need to lie flat and still and so babies and small children often require a general anaesthetic. The bile ducts and the pancreatic duct,  shown better on an MRI scan.

ERCP (Endoscopic Retrograde Cholangio-Pancreatography)

This a specialised procedure which is not often needed. It done under a general anaesthetic. In this procedure, a flexible tube with a small camera on the end (an endoscope) passed through the mouth down into the intestine. A tiny plastic tube then passed through this endoscope into the opening of the bile duct and dye is injected to outline the choledochal cyst and the pancreatic duct.

This helps to give information about the junction of bile duct with pancreatic duct (long common channel) and if there any blockage in the bile duct due to stones etc. This investigation can sometimes stir up inflammation in the pancreas (pancreatitis) causing temporary abdominal pain and vomiting afterwards. It rarely done as it an invasive investigation.

Rarely a HIDA (liver scan)

becomes necessary, if they’re only a single cyst in the liver and the MRCP cannot confirm it to a choledochal cyst/anomaly.  § The exact nature of the choledochal cyst sometimes only becomes clear at the time of surgery when the dye injected into the bile duct system (an operative cholangiogram).

Treatment of Choledochal Cysts

The treatment of choledochal cysts is surgery. This should be done in a center that has experience of looking after children who have choledochal cysts and surgeons experienced with this kind of operation. In the common variety, the cyst is completely removed. This means removing most of the bile ducts (tubes carrying bile) outside the liver together with the gallbladder. The hepatic ducts (tubes from the liver) coming out of the liver are then attached to a loop of the child’s bowel so that the bile can drain into the bowel.

More about Choledochal Cysts:

This loop of the bowel is a specially created loop. Removing the gallbladder no important long-term effects that we know of. A liver biopsy may also be taken at the time of surgery to seeing if the liver healthy or damaged. In babies with a cyst discovered by ultrasound scan but who have no symptoms, there is debate about the best time to perform surgery. Children’s surgeons who specialize in liver and bile duct surgery often recommend early surgery, generally at about six months of age.

Complications of surgery:

There are risks as with any other surgery but these are not common. For example, there is a small risk of bleeding and infection. They’re also a risk of leakage and narrowing where the bile ducts are joined to the bowel. The operation generally very successful. Most of the time, children recover rapidly and able to go home within one week after surgery. They are then seen in the outpatient clinic from time to time when a blood test (to check liver function) and an ultrasound scan may performed.

long term Outlook after surgery:

The majority (90% or more) of children remain well and grow up to be healthy adults. A small number (10% or less) may get problems such as cholangitis. Cholangitis an infection of the bile ducts within the liver. If it occurs it generally happens in the first few months after surgery. If a child becomes unwell after surgery e.g. has a temperature, it is important to seek medical advice. Some children require further surgery, for example, because the joint between the bile ducts and the bowel has narrowed down. In a very small number of patients, there a small, long-term risk of other complications including cancer of the bile ducts in adult life. This extremely rare if the cyst removed properly (not leaving behind a portion of the cyst or delaying the surgery for a long time).

Rarely, the liver scarred (cirrhosis) when a choledochal cyst is first diagnosed. In such cases, medical monitoring necessary after the cyst removed because further problems can develop and these need to recognize early.

If a choledochal cyst is left untreated, it may lead to major complications. These can include:

Liver damage (fibrosis and cirrhosis)

Infection (cholangitis)

Bile duct damage

The cyst may burst or leak

Problems with food absorption and growth

Bleeding § Stone formation (gallstones) in the cyst

Pancreatitis (inflammation in the pancreas) and damage to the pancreas and its duct

Risk of cancer developing within the bile tubes or in the gallbladder