What Is Biliary Atresia?
Biliary atresia is a gastrointestinal disorder in which the biliary system is closed or absent. The biliary system is the network of tiny tubular structures and ducts that drain bile from the liver to the small intestine, where it helps the digestive process. Bile is a liquid secreted by liver cells, made up of cholesterol, bile salts and waste products (including bilirubin). Biliary atresia progressively destroys the bile ducts that carry bile from the liver to the intestine, beginning outside the liver and later affecting bile ducts inside the liver. The damaged ducts prevent the draining of bile from the liver; as a result, bile trapped inside the liver causes damage and scarring that can lead to cirrhosis.
As the liver becomes scarred, it presses against the walls of the veins. This constricts the veins and blood cannot pass through them properly. The result is portal hypertension (high blood pressure in the portal vein).
This congenital disorder begins to progress very soon after birth. In its most common form, extrahepatic biliary atresia, ducts outside the liver are affected first.
Although it is relatively rare (occurring in 1 out of every 10,000 live births), biliary atresia is the most common liver disease that requires transplantation. On average, there is one case of biliary atresia out of every 15,000 live births. It occurs slightly more often in females than in males (1.4:1), and affects children of all races. In the United States, approximately 300 new cases of biliary atresia in infants are diagnosed each year.
The cause of biliary atresia is not known. Researchers believe that auto-immune mechanisms may be partly responsible; recent research suggests that biliary atresia could be triggered by a viral infection in susceptible infants. It is also thought that there are two kinds of biliary atresia: Embryonic (fetal) and perinatal. The perinatal type is often associated with a later onset of jaundice, and may be caused by environmental factors.
What is known for certain is that biliary atresia affects only newborns; it is not hereditary; it is not contagious; and it is not preventable. Biliary atresia is not caused by anything the mother did during pregnancy.
Biliary Atresia Symptoms in Children
Symptoms of biliary atresia usually begin to appear between two and six weeks after birth, and include:
- Jaundice (a yellow appearance of the skin and whites of the eyes) that does not improve within one to two weeks
- Dark yellow or brown urine, due to excessive bilirubin in the bloodstream that passes to the kidneys
- Pale or clay-colored (acholic) stools, an indication that very little or no bile (which gives bowel movements their normal color) is reaching the intestine
- Enlarged liver that feels harder than normal, enlarged spleen
- Poor weight gain
Biliary Atresia Diagnosis
Because early biliary atresia diagnosis of this disease is important for successful treatment, infants who are jaundiced after four weeks of age are usually evaluated for biliary atresia. The baby's physician may recommend some or all of these tests to confirm or rule out the diagnosis:
- Blood tests that measure liver function and blood clotting factors, as well as a CBC (complete blood count)
- Liver biopsy (bi-op-see)
- Ultrasound, to identify any clear abnormalities in the liver or in other organs
- A nuclear scan, which tracks bile flow from the liver
- Sometimes, exploratory surgery is performed to examine the liver and bile ducts
Biliary Atresia Treatment
Some complications of biliary atresia can be treated temporarily with medications and special diets; liquid vitamin supplements can be given orally to help lessen deficiencies.
The preferred biliary atresia treatment is the Kasai procedure, a surgical method that can help re-establish bile flow from the liver to the intestine by joining the two directly. Surgeons begin the procedure, also called a Roux-en-Y, by removing the diseased bile ducts outside the liver. A segment of the small intestine is used to attach the small intestine directly to the liver at the spot where bile is found or expected to drain. The segment of intestine that connects to the liver also connects to the rest of the intestine, forming a Y-shaped connection. Surgeons have found that they achieve better results if the Kasai is done during the infant's first eight weeks of life.
In approximately 80 percent of infants who undergo a biliary atresia Kasai procedure, bile flow is re-established. Between 25 and 30 percent of these infants will have good or complete bile flow after surgery, with normal levels of bilirubin. The other 50% will have some bile flow. The remaining 20–25% are not helped by the Kasai procedure; they gain little or no bile flow. In these cases, the infants will require liver transplantation. Liver transplantation is the only cure for biliary atresia.
Learn about other Liver Disease States.
