BILIARY ATRESIA

DEF: Progressive atresia or hypoplasia of any portion of the biliary system.
ETIOL: The incidence of biliary atresia ranges from 1 in 8,000 to 1 in 20,000 live births. The disorder appears to be acquired rather than a result of abnormal development, based on the rarity of biliary atresia in autopsied fetuses and premature newborns. One causative factor is believed to be infection with reovirus type 3.
CLIN: Infants with biliary atresia are typically born at term and have a normal birth weight. Jaundice develops at age 3 to 6 weeks in otherwise well-appearing, thriving infants. Fifteen percent of infants may have associated defects, including polysplenia (i.e., splenic tissue divided into several equally sized masses), cardiovascular anomalies, and malrotation of the intestine. Family history is usually negative.
STUDIES: Stool is acholic, collected duodenal fluid lacks bilirubin pigment or bile acids, and abdominal ultrasound may show absence of the gallbladder. Radionuclide hepatobiliary imaging demonstrates rapid uptake by the liver without intestinal excretion. Characteristic pathologic findings from percutaneous liver biopsy include bile duct proliferation, bile plugs, and portal and perilobular fibrosis. If the diagnosis is still uncertain after biopsy, surgical exploration with intraoperative cholangiography is used. This procedure enables recognition of biliary atresia and exclusion of other forms of bile duct disease, including stenosis or common bile duct perforation.
TX: If biliary obstruction occurs as a discrete lesion, surgical intervention is directed at drainage of patent portions of bile duct proximal to the atresia. Commonly, the atretic area extends above the level of the porta hepatis and affects intrahepatic bile ducts, making drainage difficult. In 80% of cases, a noncorrectable atresia is found. In these infants, further exploration is indicated to establish drainage of any small, persisting bile duct remnants. This procedure, known as the Kasai hepatoportoenterostomy, consists of transection of the porta hepatis followed by apposition of a Roux-en-Y loop of intestine. The success rate is 90% in infants younger than 2 months. In addition to infant age, the size of the residual duct lumina found during surgery is a factor in the success of this procedure; diameters less than 150 µm are associated with a poor prognosis. Treatment is not definitive, and patients may have progressive liver disease and bouts of bacterial cholangitis, requiring prompt treatment and nutritional support. Biliary atresia without intervention is universally fatal, with the mean age of death younger than 1 year. The Kasai procedure offers valuable time for the infant to grow before hepatic transplantation is necessary. Liver transplantation is essential in infants in whom the Kasai procedure fails, who are referred late (older than 120 days), and who develop liver failure despite some degree of biliary drainage.