Biliary atresia
Biliary atresia is a chronic, progressive liver problem that becomes evident shortly after birth. Tubes inside and outside the liver, called bile ducts, normally allow a liquid produced by the liver called bile to drain into the intestines and kidneys. Bile aids in digestion and carries waste products from the liver to the intestine and kidneys for excretion. In biliary atresia, bile ducts that are located inside or outside the liver are blocked. When the bile is unable to leave the liver through the bile ducts, the liver becomes damaged and many vital body functions are affected.
What causes biliary atresia?
- The cause of biliary atresia is not known.
- Some researchers and physicians believe that babies are born with biliary atresia, implying the problem with the bile ducts occurred during pregnancy while the liver was developing.
- Others believe that the disease begins after birth, and may be caused by exposure to infections or exposures to toxic substances.
- Biliary atresia does not seem to be linked to medications the mother took, illnesses the mother had, or anything else the mother did during her pregnancy.
- Currently, there is not a genetic link known for biliary atresia. The disease is unlikely to occur more than once in a family.
How often does biliary atresia occur and who is at risk?
- Biliary atresia is the most common cause of chronic liver disease in neonates.
- Biliary atresia occurs once in every 10,000 to 20,000 births.
- Asian populations are most frequently affected. African Americans are affected approximately twice as much as Caucasians.
Why is biliary atresia a concern?
Biliary atresia causes liver damage and affects numerous important processes that allow the body to function normally. It is a life-threatening disease and is fatal without treatment.
The symptoms
Infants with biliary atresia usually appear healthy at birth. Most often, symptoms develop between two weeks to two months of life, and may include:
- Jaundice – A yellow discoloration of the skin and whites of the eyes due to an abnormally high level of bilirubin (bile pigment) in the bloodstream, which is then excreted through the kidneys. High levels of bilirubin may be attributed to inflammation or other abnormalities of the liver cells, or blockage of the bile ducts. Jaundice is usually the first sign, and sometimes the only sign, of liver disease.
- Dark urine
- Light colored stools
- Distended abdomen
- Weight loss
Symptoms of biliary atresia may resemble other liver conditions or medical problems. Consult your child's physician for a diagnosis.
The diagnosis
A physician or healthcare provider will examine your child and obtain a medical history. Several diagnostic procedures are done to help evaluate the problem and may include the following:
- Blood tests
- Liver enzymes – Elevated levels of liver enzymes can alert physicians to liver damage or injury, since the enzymes leak from the liver into the bloodstream under these circumstances.
- Bilirubin – Bilirubin is produced by the liver and is excreted in the bile. Elevated levels of bilirubin often indicate an obstruction of bile flow or a defect in the processing of bile by the liver.
- Albumin and total protein – Below-normal levels of proteins made by the liver are associated with many chronic liver disorders.
- Clotting studies, such as prothrombin time (PT) and partial thromboplastin time (PTT) – Tests that measure the time it takes for blood to clot. Blood clotting requires vitamin K and proteins made by the liver. Liver cell damage and bile flow obstruction can both interfere with proper blood clotting.
- Viral studies, including hepatitis and HIV – Checking for viruses in the bloodstream can help determine the cause of the liver problems.
- Blood culture – Checking for bacterial infection in the bloodstream that can affect the liver may be used to diagnose biliary atresia.
- Imaging tests
- Abdominal ultrasound – a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view the liver, gallbladder, and bile ducts. More here on ultrasound.
- Hepatobiliary (HIDA) scan – a low radioactive isotope (technetium) is injected into the child's vein. The liver and intestine are scanned by a nuclear medicine machine. If the isotope passes through the liver into the intestine, the bile ducts are open and the child does not have biliary atresia.
The test that gives the most definitive diagnosis is a liver
biopsy. A tissue sample is taken from your child's liver and examined for abnormalities, allowing biliary atresia to be distinguished from other liver problems.