Biliary atresia is a disease of the liver and bile ducts that affects newborns. There are two distinct forms of biliary atresia. The most common form is thought to develop very shortly before or very shortly after birth and is sometimes called postnatal biliary atresia. The less common form of biliary atresia (just 10-35% of cases) is called embryonic or prenatal biliary atresia and appears to begin very early in embryonic development and is sometimes associated with other abnormalities, such as multiple spleens or situs inversus (left-right location of internal organs is reversed). In both types of biliary atresia, inflammation of the bile ducts outside the liver occurs first and progressively the ducts scar and eventually wither and close. Once the ducts are scarred shut, bile cannot flow normally to the small intestine. Liver cells produce bile at the normal rate, but it is trapped inside the liver, causing progressive liver damage.
What Causes Biliary Atresia?
Despite decades of research, the cause of biliary atresia is still unknown. Biliary atresia is not thought to be a hereditary condition as it rarely occurs more than once in the same family. In fact, the condition has been reported numerous times in just one child in a set of identical twins. There does not appear to be any link with medications taken during pregnancy. Some researchers believe the disease may be caused by exposure to a viral infection or by autoimmune damage to the bile ducts. It is likely that biliary atresia is caused by a combination of these and other unknown factors.
Presentation
Infants with biliary atresia may appear normal and healthy at birth. Often, the first symptoms appear between 2-4 weeks of age as the baby gradually becomes increasingly jaundiced (a yellow color to the skin and whites of the eyes). The absence of bile in the intestines causes the baby’s stools to become pale, or cream-colored. Excess circulating bilirubin causes the urine to become abnormally dark, or even cola-colored. The baby’s abdomen becomes more and more distended as retained bile causes the liver to swell and harden. A previously content baby may become fussy and irritable. Many babies with biliary atresia do not act sick and the symptoms appear so gradually that parents don’t notice that something is wrong. Often the child’s pediatrician is the first to notice the symptoms at a regular well baby check-up.
Diagnosis
To make the diagnosis of biliary atresia, many other causes of jaundice must first be ruled out. Tests include liver function tests (blood tests), liver biopsy, HIDA scan (a nuclear scan of the liver and biliary tree), and finally, exploratory surgery and intraoperative cholangiogram. If examination of the bile ducts reveals scarring and complete closure of the biliary tree, the diagnosis is confirmed. At this point, surgical correction, called the Kasai Procedure, is immediately attempted.
Treatment
Biliary atresia is an irreversible problem that cannot be treated with medication. However, two different operations can be performed that will allow the child with biliary atresia to live longer and have a better quality of life. These operations are the Kasai Procedure and if that fails, liver transplantation.
Kasai Procedure
The Kasai Procedure, published in the U.S. in 1968 by Dr. Morio Kasai, involves removing the damaged bile ducts and making a new duct using a section of the baby’s small intestine. One end of the small intestine is attached to the base of the liver where there may be microscopic ducts that are still open. The other end of the section joins to the rest of the intestine and creates a passageway for bile to flow out of the liver.
Success rates for the Kasai Procedure are directly related to the baby’s age. Biliary atresia is a progressive inflammatory disease, therefore the earlier it is diagnosed, the sooner corrective surgery can be attempted and the better the results. Many studies have shown significantly improved results when surgery is performed before the age of 2 months. Between 2 – 3 months, success rates drop dramatically. After 3 months of age, success is limited. Therefore, jaundiced infants over the age of 2 weeks should be promptly evaluated.
The Kasai Procedure has revolutionized the outlook for infants with biliary atresia. Prior to the development of the Kasai Procedure, children with biliary atresia usually died of liver failure within 2 years. Today, in the U.S., about 60-80% of babies will achieve bile flow following the Kasai Procedure. As many as 20% may survive into adulthood with good health and normal activities. About 20% do not gain any benefit from the Kasai Procedure and in these cases the infant is immediately referred for transplant.
Complications after the Kasai Procedure
Because metabolism of carbohydrates and proteins that occur in the liver may be impaired, and the amount of bile in the intestine to aid in the digestion of fats may be reduced, the nutritional status of children with biliary atresia is of special concern and is monitored closely. Special infant formulas containing medium chain triglycerides (a more readily absorbed form of fat) may be required to optimize growth. In addition, vitamin A, D, E & K (the fat-soluble vitamins) supplements are given. Maintaining the child’s nutritional status at a level where growth and development continue at an acceptable rate is critically important. Tube feedings may be needed to increase oral intake and weight gain.
It is normal for bacteria to be present in the intestine, but not inside the liver. Unfortunately, after the Kasai Procedure, bacteria from the portion of intestine used by the surgeon to create the new bile duct may travel up into the liver and cause an infection known as ascending cholangitis. This is a common problem and a serious one because further damage to the liver may occur. Intravenous antibiotics are begun immediately whenever ascending cholangitis is suspected.
Many infants and children develop pruritus (itching) due to increased concentration of bile salts in the blood and tissues. Severe, uncontrollable pruritus is miserable and can be considered an indication for transplant.
Even when there is good bile flow, in time, a significant number of patients develop cirrhosis and changes in blood flow through the liver, called portal hypertension. Portal hypertension results in an enlarged spleen and may produce abnormalities such as easy bruising of the skin, nosebleeds, retention of body fluids, and enlarged, weak veins (varices) in the esophagus and stomach. Increases in pressure in these weakened veins can cause significant gastrointestinal bleeding. The complications of cirrhosis and portal hypertension eventually lead to the need for liver transplantation in the majority of long-term survivors.
Liver Transplantation
When adequate bile flow cannot be achieved with the Kasai procedure, or when cirrhosis and portal hypertension cause unmanageable complications, liver transplantation is the second treatment option.
A liver transplant operation removes the damaged liver and replaces it with a new liver from a donor. The new liver can be either a whole liver or part of a liver received from someone who has died, or it can be part of a liver received from a living donor whose blood and tissue types match the child’s. After surgery, the child’s health may improve dramatically; however, rejection of the new organ is always a threat. Rejection occurs due to the body’s normal immune mechanisms that help fight against invasion of viruses, tumors, and other foreign substances. To prevent this normal body response from fighting against the transplanted liver, a rigorous regimen of anti-rejection medications must be taken for life.
Conclusion
Early diagnosis and surgical correction are critical to achieving the best outcome in biliary atresia. When the Kasai Procedure fails, or when complications can no longer be managed effectively, the child is referred for liver transplantation. Together, the Kasai Procedure and liver transplantation give children with biliary atresia hope for long, happy, and active lives.
References
American Liver Foundation. Biliary atresia. liverfoundation.org/education/info/biliaryatresia/
Biliary atresia from emedicine.com/ped/topic237.htm 
