Choledochal means “of or relating to the common bile duct.” It comes from the Greek words chole meaning “bile” and dochus meaning “containing.” The common bile duct is the pathway through which bile, which assists with digestion, flows from the liver, where it is produced, to the pancreas and from there to the duodenum. Connecting the common bile duct to the liver are the right and left hepatic ducts. A choledochal cyst is a cyst that occurs somewhere in the bile duct.
Choledochal cysts are congenital, meaning they’re present at birth, and they’re rare. The cause is unknown. A choledochal cyst can be intrahepatic, occurring within the bile duct inside the liver, or extrahepatic, occurring in the portion of the bile duct external to the liver.
Choledochal cysts have five different types, with the most common being a cystic dilation of the extrahepatic biliary duct. About half the cases involving a choledochal cyst are of this type. The next three most frequently occurring types of cyst are differentiated by their location. One is found as a pouch opening from the extrahepatic biliary duct, one is a cycst found within the duodenal wall, and one involves cysts in both the intrahepatic and extrahepatic ducts. The type of choledochal cyst that is least common in Caroli’s disease, which is characterized by multiple intrahepatic cysts that group in clusters.
Coledochal cysts occur most often in Japan. They are more common in females than males, but in the West, are only seen in between 1 in 100,000 and 150,000 people. Often, people are not diagnosed until they are adults, although with ultrasound, they can be diagnosed prenatally.
If the diagnosis is not made early, a child may exhibit symptoms. These can include generalized symptoms like fever and nausea, which could be indicative of many things. Pancreatitis, jaundice, an abdominal mass, or pain around the liver are more specific, but certain diagnosis must be done by a physician.
The liver in an adult normally ways three pounds (1.36 kg). Choledochal cysts become filled with bile and can eventually grow to contain one to two quarts (.95–1.89 liters). Since water weighs slightly more than two pounds/quart (.91 kg/liter), we can guess that the cysts may come to weigh more than the liver itself.
There are several potential risks of having a choledochal cyst. The cyst can obstruct the flow of bile, and cause jaundice or cirrhosis. The cells that line the cyst can have pre-cancerous changes. This can increase the person’s chance of having gallbladder cancer develop. A choledochal cyst is most often treated with surgery.
