This defect causes bile to collect in the liver and can lead to irreversible liver damage.
Typical symptoms include a yellowish discoloration of the skin (jaundice), dark urine, pale stools, and an enlarged liver.
The diagnosis is based on blood tests, radionuclide scanning, and surgical examination of the liver and bile ducts.
Surgery is needed to create a path for bile to drain from the liver.
Bile, a digestive fluid secreted by the liver, carries away the liver's waste products and helps digest fats in the small intestine. Bile ducts carry the bile from the liver to the intestine.
In biliary atresia, starting several weeks to months after birth, the bile ducts progressively narrow and become blocked. Thus, bile cannot reach the intestine. It eventually accumulates in the liver and then escapes into the blood, causing a yellowish discoloration of the skin (jaundice). Progressive, irreversible scarring of the liver, called cirrhosis, starts by the age of 2 months if the defect is not treated.
Doctors do not know why biliary atresia develops, but some infection-causing organisms and gene defects may be involved. About 15 to 25% of infants have other birth defects.
(See also Overview of Digestive Tract Birth Defects.)
In infants with biliary atresia, the urine becomes dark, the stools become pale, and the skin becomes increasingly jaundiced. These symptoms and an enlarged, firm liver are usually first noticed about 2 weeks after birth.
By the time infants are 2 to 3 months old, they may have stunted growth, be itchy and irritable, and have large veins visible on their abdomen, as well as a large spleen.
To prevent cirrhosis, doctors must diagnose and treat biliary atresia within the first 1 to 2 months of the infant's life.
To make the diagnosis of biliary atresia, a doctor does a series of blood tests and an imaging test using a radioactive tracer. The tracer is injected into the infant's arm, and a special scanner tracks the flow of the tracer from the liver into the gallbladder and small intestine (called hepatobiliary scanning—a type of radionuclide scanning). Ultrasonography of the abdomen may be helpful.
If the defect is still suspected after these tests, surgery (which consists of examination of the liver and bile ducts and a liver biopsy) is done to diagnose the defect.
Biliary atresia gets progressively worse. If untreated, it causes irreversible scarring of the liver (cirrhosis) by the time the infant is several months of age, liver failure, and death by 1 year of age.
Surgery is needed to create a path for bile to drain from the liver. The path is made by sewing a loop of intestine to the liver where the bile duct comes out. This operation should be done in the first month of life, before the liver has become scarred. If the operation is unsuccessful, infants need liver transplantation. Even when the operation is successful, about half of infants continue to have worsening liver disease and ultimately need liver transplantation. The remaining infants can lead normal lives.
After the operation, infants are often given antibiotics for a year to prevent inflammation of the bile ducts. They may also be given a drug called ursodiol. Ursodiol increases the flow of bile, which helps keep the bile drainage path open. Because good nutrition is important, infants are also given supplemental fat-soluble vitamins.
Infants who cannot have the surgery usually require liver transplantation by 1 year of age.