progressively narrow and become blocked after birth, preventing bile from reaching the intestine.This defect causes bile to collect in the liver and can lead to irreversible liver damage.
Typical symptoms include a yellowish discoloration of the skin (jaundice), dark urine, pale stools, and an enlarged liver.
The diagnosis is based on blood tests, radionuclide scanning, and surgical examination of the liver and bile ducts.
Surgery is needed to create a path for bile to drain from the liver.
Bile, a digestive fluid secreted by the liver, carries away the liver's waste products and helps digest fats in the small intestine. Bile ducts Gallbladder and Biliary Tract The gallbladder is a small, pear-shaped, muscular storage sac that holds bile and is interconnected to the liver by ducts known as the biliary tract. (See also Overview of the Liver and Gallbladder... read more carry the bile from the liver to the intestine.
In biliary atresia, starting several weeks to months after birth, the bile ducts progressively narrow and become blocked. Thus, bile cannot reach the intestine. It eventually accumulates in the liver and then escapes into the blood, causing a yellowish discoloration of the skin (jaundice Jaundice in the Newborn Jaundice is a yellow color to the skin and/or eyes caused by an increase in bilirubin in the bloodstream. Bilirubin is a yellow substance formed when hemoglobin (the part of red blood cells... read more 
). Progressive, irreversible scarring of the liver, called cirrhosis Cirrhosis of the Liver Cirrhosis is the widespread distortion of the liver's internal structure that occurs when a large amount of normal liver tissue is permanently replaced with nonfunctioning scar tissue. The scar... read more 
, starts by the age of 2 months if the defect is not treated.
Doctors do not know why biliary atresia develops, but some infection-causing organisms and gene defects may be involved. About 15 to 25% of infants have other birth defects.
(See also Overview of Digestive Tract Birth Defects Overview of Digestive Tract Birth Defects The digestive organs may be incompletely developed or abnormally positioned, causing blockages, or the muscles or nerves of the digestive tract may be defective. Symptoms depend on the location... read more .)
Symptoms of Biliary Atresia
In infants with biliary atresia, the urine becomes dark, the stools become pale, and the skin becomes increasingly jaundiced. These symptoms and an enlarged, firm liver are usually first noticed about 2 weeks after birth.
By the time infants are 2 to 3 months old, they may have stunted growth, be itchy and irritable, and have large veins visible on their abdomen, as well as a large spleen.
Diagnosis of Biliary Atresia
Blood tests
Radionuclide scanning
Ultrasonography
Surgery
To prevent cirrhosis, doctors must diagnose and treat biliary atresia within the first 1 to 2 months of the infant's life.
To make the diagnosis of biliary atresia, a doctor does a series of blood tests and an imaging test using a radioactive tracer. The tracer is injected into the infant's arm, and a special scanner tracks the flow of the tracer from the liver into the gallbladder and small intestine (called hepatobiliary scanning—a type of radionuclide scanning Radionuclide (Radioisotope) Scanning Imaging tests of the liver, gallbladder, and biliary tract include ultrasonography, radionuclide scanning, computed tomography (CT), magnetic resonance imaging (MRI), endoscopic retrograde cholangiopancreatography... read more ). Ultrasonography Ultrasonography Ultrasonography uses high-frequency sound (ultrasound) waves to produce images of internal organs and other tissues. A device called a transducer converts electrical current into sound waves... read more 
of the abdomen may be helpful.
If the defect is still suspected after these tests, surgery (which consists of examination of the liver and bile ducts and a liver biopsy Biopsy of the Liver Doctors can obtain a sample of liver tissue during exploratory surgery, but more often they obtain a sample by inserting a hollow needle through the person's skin and into the liver. This type... read more ) is done to diagnose the defect.
Prognosis
Biliary atresia gets progressively worse. If untreated, it causes irreversible scarring of the liver (cirrhosis Cirrhosis of the Liver Cirrhosis is the widespread distortion of the liver's internal structure that occurs when a large amount of normal liver tissue is permanently replaced with nonfunctioning scar tissue. The scar... read more ) by the time the infant is several months of age, liver failure, and death by 1 year of age.
Treatment of Biliary Atresia
Surgery
Frequently liver transplantation
Surgery is needed to create a path for bile to drain from the liver. The path is made by sewing a loop of intestine to the liver where the bile duct comes out. This operation should be done in the first month of life, before the liver has become scarred. If the operation is unsuccessful, infants need liver transplantation. Even when the operation is successful, about half of infants continue to have worsening liver disease and ultimately need liver transplantation. The remaining infants can lead normal lives.
After the operation, infants are often given antibiotics for a year to prevent inflammation of the bile ducts. They may also be given a drug called ursodiol. Ursodiol increases the flow of bile, which helps keep the bile drainage path open. Because good nutrition is important, infants are also given supplemental fat-soluble vitamins Fat-soluble vitamins Vitamins are a vital part of a healthy diet. The recommended dietary allowance (RDA)—the amount most healthy people need each day to remain healthy—has been determined for most vitamins. A safe... read more .
Infants who cannot have the surgery usually require liver transplantation Liver Transplantation Liver transplantation is the surgical removal of a healthy liver or sometimes a part of a liver from a living person and then its transfer into a person whose liver no longer functions. (See... read more by 1 year of age.
