*2.5.3 Diagnosis*

*Congenital Anomalies in Newborn Infants - Clinical and Etiopathological Perspectives*

*Normal anatomy of the hepatobiliary tree and its relationship to the pancreas and duodenum. (A) Choledocal cyst type 1: fusiform dilation of the extrahepatic duct common bile duct. (B) Choledocal cyst type 2: isolated diverticulum off the common bile duct. (C) Choledocal cyst type 3: supraduodenal choledococele. (D) Choledocal cyst type 4: cystic dilation of intra- and extra-hepatic bile ducts. (E) Choledocal cyst type 5,* 

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**Figure 3.**

*dilation of intra-hepatic ducts only.*

While abdominal ultrasound and hepatobiliary 99-Tc IDA scan are useful, MRCP best delineates the anatomy of the biliary tree and is the diagnostic test of choice. There are five types (**Figure 3**). Type 1 is the most common and presents as saccular or fusiform dilation of the common bile duct (CBD; **Figure 3A**). Intrahepatic ducts are normal. Type 2 is an isolated CBD diverticulum (**Figure 3B**). Type 3 is a choledochocele, in which there is cystic dilation of the supra-duodenal CBD, prior to its junction with the pancreatic duct (**Figure 3C**). In type 4 disease, intra- and extra-hepatic bile ducts are dilated whereas in type 5 disease only intrahepatic ducts are dilated (**Figures 3D, E**).
