Biliary atresia is a rare condition in which the biliary system (a network of small tubes that help carry bile from the liver to the small intestine) has not developed normally in the womb or becomes blocked shortly after birth. This means that bile, the liquid made by the liver to help with digestion and carry away waste products (including bilirubin), gets trapped, causing damage to liver cells. Since the bile does not reach the intestine as it should, there are problems digesting food.

The exact cause of biliary atresia is not known. Some cases may be caused by problems with the immune system or an infection. Children with biliary atresia also may have other congenital problems involving the heart, blood vessels, intestine, or spleen. Biliary atresia does not run in families, is not contagious, is not preventable, and affects only newborns. It affects one of every 10,000 to 15,000 babies born, with approximately 300 new cases being diagnosed in the United States each year.

An infant with biliary atresia typically has no problems at birth, but then develops yellow skin and eyes (jaundice), light-colored stools, and dark urine at 2 to 3 weeks of age, due to the buildup of bilirubin in the blood. The baby's belly may become swollen and the liver may feel bigger than usual. As the jaundice worsens, the baby may start to lose weight and become irritable. If not treated, biliary atresia can be fatal.

It is important to remember that most babies have some amount of jaundice in the first few days of life because the liver is not fully working yet. However, jaundice should never be ignored because it may also be a sign of a more serious illness (for example, biliary atresia). Any baby with jaundice should be evaluated by a health-care provider. If biliary atresia is suspected, tests may be needed to make the diagnosis, including blood work, X-rays, and ultrasound.