congenital biliary malformation

Congenital biliary tract malformations generally include congenital biliary atresia, congenital bile duct dilatation, and rare biliary strictures. Congenital biliary atresia is biliary obstruction caused by congenital developmental disorders and is a common cause of prolonged obstructive jaundice in the neonatal period. The lesion may involve the entire biliary tract or only part of the intrahepatic or extrahepatic bile ducts, with extrahepatic biliary atresia being the most common, accounting for 85%–90%. The incidence is higher in females than in males. Congenital bile duct dilatation can occur in any part of the intrahepatic or extrahepatic bile ducts; because it commonly occurs in the common bile duct, it was formerly called congenital choledochal cyst. Based on its pathological features, it has recently been considered more appropriate to call it bile duct dilatation. Congenital bile duct dilatation is more common in Eastern countries, especially Japan. It is more common in females, with a male-to-female ratio of approximately 1:3–4. Symptoms may appear as early as infancy, and about 80% of cases present during childhood.