Biliary atresia
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.
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.
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 it?
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 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.
What is the treatment?
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.
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.
Vitamin deficiencies
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.
Infections
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 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.
No precautions are possible as biliary atresia occurs without warning, only in
infants and is not passed from one person to another.
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