Worsening jaundice during the first month of life means a liver problem is present. The specific diagnosis of biliary atresia requires blood and x-ray tests, and sometimes a liver biopsy. If biliary atresia is suspected, the newborn is usually referred to a specialist such as:

• A pediatric gastroenterologist who is an expert in digestive diseases of children.
• A pediatric hepatologist who is an expert in liver disease of children.
• A pediatric surgeon who specializes in surgery of the liver and bile ducts.

Initial Tests

The doctor will press on the baby’s abdomen to check for an enlarged liver or spleen and order blood, urine, and stool tests to check for liver problems. The level of bilirubin in the blood will be measured and special tests for other causes of liver problems will be done.

• Ultrasound of the Abdomen and Liver
  Ultrasound tests produce an image on a computer screen using sound waves. Ultrasound tests can show whether the liver or bile ducts are enlarged and whether tumors or cysts are blocking the flow of bile. An ultrasound cannot be used to make a diagnosis of biliary atresia, but it does help rule out other common causes of jaundice.
• Liver Scans
  Liver scans are special types of x-rays that use substances that can be detected by cameras to create an image of the liver and bile ducts. One such test is called hepatobiliary iminodiacetic acid (HIDA) scanning. HIDA scans trace the path of bile in the body and can show whether bile flow is blocked.
• Liver Biopsy
  If another medical problem is not found to be the cause of jaundice, a liver biopsy may be recommended. For a liver biopsy, the infant is sedated and a needle is passed through the skin and then quickly in and out of the liver. A small piece of liver, about the size of a pencil lead, is obtained for examination using a microscope. A liver biopsy will usually show whether biliary atresia is likely. A biopsy can also help rule out other liver problems, such as hepatitis.

Source: digestive.niddk.nih.gov