Cells within the liver secrete a liquid called bile, which is made up of cholesterol, bile salts and waste products, including bilirubin. A network of tubular structures and tiny ducts form the biliary system to drain bile from the liver to the small intestine where it aids in the digestive process. Biliary atresia is the closure or disappearance of the biliary system.
Biliary atresia is a progressive inflammatory process that begins very soon after birth. In the most common form, called extrahepatic biliary atresia, the delicate ducts outside the liver are affected first. White blood cells invade the ducts, which become damaged and may whither or completely disappear. Bile is trapped inside the liver and rapidly causes damage and scarring to the liver cells. Further scarring of the liver tissue may result in cirrhosis.
On average, there is one case of biliary atresia out of every 15,000 live births. Females are affected slightly more often than males. In the United States, approximately 300 new cases are diagnosed each year.
What causes biliary atresia?The cause of biliary atresia is unknown. Auto-immune mechanisms may be partly responsible for the progressive process that takes place. Recent research suggests that a viral infection in susceptible infants could result in biliary atresia. About 10% of cases have other associated congenital defects in the heart, blood vessels, intestine, or spleen.
Although the cause is uncertain, it is known that biliary atresia affects only newborns; it is not hereditary; it is not contagious; and it is not preventable. Parents should be assured that biliary atresia is not caused by anything the mother did during pregnancy.
DiagnosisThe usual history is a full term infant who appears normal at birth but develops jaundice after the age of 2 to 3 weeks. The infant has yellow eyes and skin, light-colored stools and dark urine caused by the build up of bilirubin in the blood. The abdomen may be swollen with a firm, enlarged liver. Weight loss and irritability develop as the level of jaundice increases.
Many tests are needed to rule out other possible causes of jaundice and diagnosis biliary atresia: