Biliary atresia begins in early infancy and causes damage to the liver due to the destruction of ducts which carry bile from the liver to the small intestine. Early damage mainly affects the major bile duct outside the liver which is why this disease is also called extrahepatic biliary atresia; later damage mainly affects bile ducts in the liver.
What is biliary atresia?
Biliary atresia is a relatively rare disease affecting about one in every 10,000 to 20,000 infants soon after birth. The bile duct outside the liver carrying bile from the liver to the small intestine is damaged. This prevents bile from leaving the liver so it is accumulated there causing progressive damage to the liver tissue. In addition, there is ongoing damage to smaller bile ducts inside the liver. Unless bile flow can be established, liver function is gradually lost and affected children rarely survive beyond two years.
What is bile?
Bile is a yellow-green fluid made in the liver and stored in the gallbladder. From there, it flows through the common bile duct to the small intestine, where it aids in digesting and absorbing dietary fats, and fat-soluble vitamins.
What causes the disease?
The cause of biliary atresia is unknown. It is not contagious, so it cannot be passed from one child to another. It is not hereditary, nor can it be attributed to any specific aspect of prenatal care. Researchers currently believe that some process causes inflammation and blockage of the bile ducts.
What are the typical symptoms?
Biliary atresia is usually diagnosed during the first two months of life. Common signs are:
- newborn jaundice that does not improve by four weeks of age especially if it appears after two weeks of age
- dark urine and pale, clay-coloured stools
- enlarged liver or swollen abdomen
Since the symptoms of biliary atresia may also be experienced in other diseases, several tests are necessary to make a diagnosis. The following tests are performed: blood, urine and stool samples are analyzed; the liver and bile ducts are examined with ultrasound; a liver scan showing the liver and bile ducts is performed; a liver biopsy is obtained. If the test results suggest biliary atresia, an operation is performed to examine the bile ducts and an x-ray is taken during the operation to determine whether the bile duct is blocked.
How is the disease treated?
It is essential that the bile flow be established. Otherwise, the liver will suffer more damage, resulting in liver failure. The most common treatment is an operation called the Kasai procedure (named for the surgeon who developed it). In this operation the damaged duct outside the liver is removed and replaced with a new drainage system made from a piece of the small intestine. This may partially or fully alleviate the jaundice, but it will not reverse the liver damage that has already occurred or prevent any low-grade ongoing damage. The Kasai procedure is successful in one-third to one-half of all patients and if jaundice is fully relieved, most children will grow and develop quite normally. Cirrhosis, or scarring of the liver, generally occurs despite a successful Kasai procedure.
What happens if the initial treatment fails?
If the Kasai procedure fails to establish bile flow, the child will suffer ongoing health problems such as vitamin deficiencies, delayed development and inhibited growth as well as bleeding into the gastrointestinal tract and infections.
Vitamins A, D, E and K are fat-soluble, and the body can use them only when they are bound to fat. If there is too little bile in the intestine for fat digestion, the baby may suffer from vitamin deficiency and may need to take supplements by mouth.
Delayed development and inhibited growth
If insufficient bile reaches the intestine, the baby will not be able to digest the fat in its food. This makes it difficult to gain weight.
A child with biliary atresia may look quite jaundiced if bile flow has not been achieved; the liver may become enlarged, creating a 'pot-bellied' appearance. Frequent hospitalizations and long periods of feeling unwell may delay development of sitting, walking and other activities. Mental development, however, is usually normal.
Bleeding into the gastrointestinal tract
Liver damage may interfere with normal blood flow through the liver. As a result, blood from the intestine by-passes the liver, causing increased blood pressure in the veins of the stomach and esophagus. These veins may become enlarged and may begin to leak, causing internal bleeding.
Especially in children in whom the Kasai procedure relieves jaundice, infection can be a problem. Infections can develop in the new drainage tube. Symptoms of infection include fever and increasing jaundice. Infections are treated with antibiotics.
When is a liver transplant necessary?
When it proves difficult or impossible to achieve adequate bile flow and liver failure develops, liver transplantation is a final option. Replacing the liver in this way is successful in about 75% of cases. The largest obstacle to the successful treatment of all children with liver failure from biliary atresia is the relative lack of liver donors in this age group for transplantation.
What precautions should be taken?
No precautions are possible as biliary atresia occurs without warning, only in infants and is not passed from one person to another.
What else can we learn about?
Identifying causes of biliary atresia and other liver diseases in children is the key research goal. The Canadian Liver Foundation supports educational programs and research into the causes, diagnoses, prevention and treatment of liver disease.
If you would like more information on biliary atresia or any other liver disease, please contact us.
To read about research projects on Pediatric liver disease click here
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