Biliary atresia

What is biliary atresia?

Biliary atresia is a rare disease in which the tubes which drain liquid bile from the liver are progressively destroyed. This fibrosis of the biliary duct system results in a build up of bile, which damages the liver. As a result, the condition invariably leads to death from liver failure by the age of two if untreated.

However there is now effective surgery which can relieve symptoms in most cases. Liver transplant is also an option, and as a result, survival rates are now above 90 per cent.

Causes and risk factors

Biliary atresia is due to a progressive fibrosis or scarring of the bile ducts responsible for draining bile from the liver, which eventually leads to atresia or loss of the biliary system. It's not clear how or why this occurs, and many factors may be involved. It may be due to a problem in the developing embryo (10 to 20 per cent – other congenital abnormalities may also be present) or around the time of birth or shortly afterwards (80 to 90 per cent). It occurs more often in Asian and African-American newborns than Caucasian.

Bile is made by the liver and helps with the digestion of fats. If bile is not removed from the liver, it builds up and begins to damage it. The baby will then develop jaundice, or a yellow colour of the skin as levels of the bile chemical bilirubin rise in the blood. Other symptoms include dark coloured urine and pale stools. Many newborn babies become jaundiced but this is usually temporary. Jaundice lasting for longer than 14 days, especially if there are other symptoms such as an enlarged liver or failure to thrive, is a worrying sign and must be investigated further.

Symptoms

A battery of tests are often required to confirm a diagnosis of biliary atresia, as the symptoms can be confused with other conditions. These tests can include:

• A blood test to look for raised levels of bilirubin and check liver enzyme levels and blood clotting
• An abdominal x-ray to look for an enlarged liver and spleen
• Abdominal ultrasound to examine the liver and bile ducts
• An scan to determine how well bile is flowing (HIDA or TEBIDA)
• A liver biopsy to determine the condition of the bile ducts and extent of cirrhosis or to rule out other causes of jaundice
• Other x-ray or endoscopy tests may be done to assess the extent of damage to the biliary system and liver

Treatment and prevention

The earlier biliary atresia is detected, the less damage it will have done to the liver and the better the chance of a successful outcome to treatment. The current target is to treat babies before they are eight weeks old.

If the liver has not yet been damaged by cirrhosis, the condition is usually treated through an operation called a Kasai portoenterostomy (or a similar procedure). This involves using a loop of bowel to form a duct to drain the bile from the liver. The operation is named after the Japanese surgeon, Professor Morio Kasai, who developed it in 1959. It was first introduced in the UK in the 1960s.

Operations can be carried out on children as young as 11 days old. The operation is extremely intricate and is best carried out in a centre with expertise in this area. For this reason it's now recommended that affected children are treated at one of three UK specialist centres (Kings College Hospital, London, Birmingham Children’s Hospital and St James’ Hospital, Leeds).

With such major surgery there is inevitably a risk of various complications both early on and in the years following it. However, most children do well, especially if the operation is done before the condition has damaged the liver. In about 60 percent of cases the Kasai procedure is successful, allowing drainage of bile, and of these children 80 percent will reach adolescence with their own livers still functioning adequately, giving them a good quality of life.

Others will need a liver transplant which currently has a greater than 95 per cent survival rate at one year.