Extrahepatic bilirubin conjugation

Possible increase in serum conjugated bilirubin Obstruction of bile flow commonly due to common bile duct stone or pancreatic carcinoma Failure of bile secretion Extrahepatic cholestasis Intrahepatic cholestasis... 

Extrahepatic biliary atresia may involve all or part of the extrahepatic bifiary tree. The gallbladder is usually absent. Involvement of the hepatic or common duct leads to the characteristic syndrome of severe cholestatic jaundice. It occurs in 1 in 10,000 births, with females more commonly affected than males. Jaundice and pruritus usually appear in the first week. Stools are pale and the urine is tea colored. Jaundice is deep, but the aminotransferases are only mildly elevated. If jaundice persists beyond 14 days of age, a direct or conjugated bilirubin measurement must be performed to exclude biliary atresia. If it is elevated, the urine should be tested for bile and the stool color inspected if the color is not green or yellow, biliary atresia is likely. Early identification of this condition is essential if these infants are to benefit fi"om the operation of portoenterostomy, which should be performed no later than 60 days after birth. If portoenterostomy is not successful, liver transplantation is the treatment of choice. Children rarely live beyond 3 years unless the lesion is surgically correctable. 

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