Biliary atresia is the congenital absence or 
closure of the ducts  that drain bile from the liver.

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.

Diagnosis

The 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:

• Blood tests may show abnormal results which indicate liver dysfunction with increased bilirubin (a chemical marker in the blood for jaundice).
• An ultrasound test may detect an absent or tiny gall bladder.
• In another test, called a HIDA scan, a special radioactive dye that acts like bilirubin is injected into the infant’s vein. In biliary atresia, the dye is taken up by the liver but cannot flow through the damaged biliary system to the small intestine.
• A special needle may be used to take a tiny piece of liver, which under a microscope may indicate features typical of an obstruction to the biliary system.
• Surgical exploration of the baby’s abdomen is necessary in most cases of suspected biliary atresia to definitively make the diagnosis.

Treatment

Bile flow is re-established in approximately 80% of infants who are operated on when younger than 3 months of age. Of these, about 50% will have some bile drainage and as many as 30% will have complete bile drainage with a return to normal bilirubin. About 20% of infants will not be helped by the Kasai procedure. In these cases, the only other treatment option is a liver transplant.

Early diagnosis of this disease is very important. If surgery is performed before the baby is 2 months old, success is much more likely. After 3 months, success of the operation is poor. For this reason, all infants who are jaundiced after the age of 4 weeks should be evaluated for biliary atresia.

Complications

The most common complication associated with the Kasai procedure is ascending cholangitis, a bacterial infection of the biliary tree. Bacteria normally found in the small intestine moves up the Roux-en-Y causing infection. Signs include unexplained fever, increased jaundice, or lighter stools. Intravenous and long-term oral antibiotics are used to prevent and treat ascending cholangitis.

Adequate bile flow is needed for the digestion and absorption of dietary fats and fat-soluble vitamins, including vitamins A, D, E, and K. When bile flow is reduced, poor growth and malnutrition may result. Special formulas containing medium-chain triglycerides (an easily digested form of dietary fat) and water-soluble vitamin supplements are often prescribed to maximize the child’s growth and development.

Formation of scar tissue eventually leads to portal hypertension in many children. Portal hypertension refers to increased pressure in the veins between the intestines and spleen to the liver. Complications include problems with bleeding and clotting; enlarged weak veins in the esophagus and stomach; and accumulation of fluid in the abdominal cavity called ascites. When these complications can no longer be treated effectively, the child is referred for liver transplantation.

What is the outcome for children with biliary atresia?

If left untreated, the result of blocked bile flow is damage to the liver such that few children survive beyond the age of two. When bile flow is only partly restored by surgery, the complications of cirrhosis will gradually develop. If the Kasai procedure is successful in draining the liver and returning the bilirubin back to normal, children may live many years with normal growth and activities. Some will grow into adulthood and some may never need a transplant.

More often, despite successful surgery, slow, progressive damage to the liver continues. When progressive cirrhosis occurs, it will eventually require liver transplantation.

Liver transplantation plays an important role in the long-term treatment of biliary atresia. Pediatric liver transplantation has evolved into a highly successful therapy and now offers significant hope for all children born with biliary atresia.