Bile duct duplication

Last revised by Daniel J Bell on 8 Apr 2023

Bile duct duplication, also known as common bile duct duplication, (although in some cases this latter terminology would be erroneous), is a rare congenital anomaly of the biliary system. A double bile duct is considered normal during early human development, but by birth, we expect to see the conventional anatomy consisting of a single common hepatic and bile duct 1,2.

The various duplications of the biliary tree are collectively very rare. For example, the double common bile duct had been reported in 56 cases globally up to 1992 3. The abnormality appears to be more common in Asian populations according to the various reported studies 1-4.

Some cases of duplicated biliary ducts are asymptomatic and found incidentally, however there seems to be increased rates of choledocholithiasis, cholangitis, gallstones, and biliary malignancy in those with these ductal anomalies 4.

A duplicated common bile duct is normal in birds, reptiles and fish. However, such an arrangement is a rare developmental abnormality in adult human biliary trees. Interestingly, a double bile duct is normal at an early stage in human embryogenesis, but this duplex ductal tree changes to form the standard solitary common bile duct that we expect to see in human anatomy 1,2,4.

Modified Choi classification of common bile duct duplication is a widely used system for classifying the duplication of the extrahepatic biliary tree 2.

A duplicated common bile duct is usually detected on MRCP or ERCP.

Andreas Vesalius (1514–1564) 5 reported the first case of a duplicated common bile duct in 1543 4.

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