Biliary atresia is a rare condition in newborn infants in which the common bile duct between the liver and the small intestine is blocked or absent.
Early surgical intervention to treat biliary atresia is critical to prevent irreversible liver damage. Once the liver fails, a liver transplant is required.
Biliary atresia is, in fact, the most common reason for liver transplantation in children in the U.S. Children age 1-2 may require liver transplantation for biliary atresia. In the longer term, 4 of 5 children with the disease will need a liver transplant before age 20. The remaining children will have less serious liver disease, but still require careful medical management and surveillance.
In biliary atresia, the bile ducts outside the liver (extrahepatic bile ducts) are abnormal and are damaged by a progressive inflammatory process. Over time, biliary strictures (narrowing of the bile ducts) form preventing bile from draining into the intestine from the liver. Bile then becomes trapped and accumulates in the liver, damaging the intrahepatic bile ducts within the liver. This leads to jaundice (yellowing of the skin), cirrhosis (buildup of scar tissue in the liver) and hepatomegaly (swelling of the liver).
The incidence of biliary atresia is approximately one in 10,000 children, with the disease being more common in males and in Asian and African-American newborns. Biliary atresia is not an inherited disease and does not run in families. Indeed, there have been cases of identical twins, where only one child has the disease. The causes of biliary atresia are not well understood. It is hypothesized that an event occurring during fetal life or at the time of birth may trigger the disease such as:
- infection with a virus or bacterium
- a problem with the immune system
- an abnormal bile component
- an error in development of the liver and bile ducts
Types of Biliary Atresia
There are two types of biliary atresia, a fetal form, which develops during fetal life and is present at birth, and a more common perinatal form, which does not become evident until the second to fourth week of the infant's life. Some children, particularly those with the fetal form of biliary atresia, have other birth defects in the heart, spleen, or intestines.
The first sign of biliary atresia is jaundice, which causes a yellowing of the the skin and whites of the eyes. Jaundice is caused by the inability of the the liver to remove bilirubin, a yellowish pigment, from the blood. Normally, bilirubin is absorbed by the liver and then released into the bile. Blockage of the bile ducts cause bilirubin and bile to build up in the blood.
Jaundice may be difficult detect because many healthy newborns have some mild jaundice during the first 1 to 2 weeks of life due to immaturity of the liver. This usually disappears by the second or third week of life. In contrast, the jaundice caused by biliary atresia deepens. Therefore, newborns with persistent jaundice after 2 weeks of life should be immediately checked for a possible liver dysfunction.
Other signs of jaundice are a darkening of the urine and a lightening in the color of bowel movements. The urine darkens from the high levels of bilirubin in the blood spilling over into the urine, while stool lightens from a lack of bilirubin reaching the intestines. Pale, grey, or white bowel movements after 2 weeks of age are clear signs of a liver problem.
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 will need to be evaluated by a pediatric liver specialist such as a pediatric hepatologist (liver disease in children), pediatric gastroenterologist, (digestive disease in children) or pediatric surgeon with expertise in surgery of the liver and bile ducts.
Biliary atresia can often be difficult to diagnose. A combination of diagnostic tests will be used to including:
- Abdominal ultrasound: An ultrasound provides an image of the liver and associated structures, identifying the anatomy and ruling out other causes of liver disease.
- HIDA (hepatobiliary iminodiacetic acid) scan: This study provides an image of bile flow from the liver, through the gallbladder and extrahepatic biliary ducts into the intestine.
- Liver biopsy: A tiny sample of liver tissue is removed with a needle and examined under a microscope by a pathologist, a physician specializing in tissue analysis. The biopsy may be helpful in determining whether surgery is necessary.
- Intraoperative cholangiogram: This test is scheduled when the diagnosis of biliary atresia is likely. During this procedure, a contrast dye is injected into the gallbladder while the flow of dye is monitored. If there is no flow of contrast into the extrahepatic biliary ducts, a diagnosis of biliary atresia is made and a Kasai procedure is performed at that time.
If biliary atresia appears to be the cause of jaundice, surgery to examine the bile ducts is performed. If the surgeon confirms the diagnosis of biliary atresia, a Kasai Procedure (hepato-portoenterostomy) is performed to reconstruct the bile ducts and restore bile flow.
In the Kasai Procedure, the blocked extrahepatic bile ducts as well as the gallbladder and replaced by a segment of the child's intestine, which is sewn directly to the liver. The surgical joining of the liver with a segment of the intestine functions as the new extrahepatic bile duct system.
If the Kasai procedure is unsuccessful, the infant will usually require a liver transplant, sometimes between ages 1 and 2. Of all infants who have had a Kasai procedure, fully half still require liver transplantation before age 5. Clinical trials are underway to improve the outcome of the Kasai or gall-bladder Kasai in infants with biliary atresia.
Children with the fetal form of biliary atresia are more likely to require liver transplants, usually sooner rather than later, than for infants with the more usual perinatal form of the disease. The need for a transplant is also affected by the arrangement of diseased bile ducts and the extent of damage.
Liver transplantation is a highly successful treatment for biliary atresia. Survival after surgery has increased dramatically in recent years. Children with biliary atresia are now surviving well into adulthood.
Improvements in transplant surgery have also led to a greater availability of livers for transplantation in children. In the past, only livers from small children were deemed a suitable match for a transplant. Today, however, advances in treatment now allow the option of "reduced size" or "split liver" transplants, in which a piece of an adult liver can be used for transplantation in a child with biliary atresia. Parents or relatives of children with biliary atresia may now be considered potential donors. Because healthy liver tissue regenerates quickly, the living donor and the child can expect their livers to grow back over time..
Philip Rosenthal, M.D., a pediatric hepatologist, and Hanmin Lee, M.D., a pediatric surgeon are, together with colleagues at other universities, are conducting a multi-center study to investigate the causes of liver disease in children including neonatal hepatitis and biliary atresia.
An additional study is creating a database of clinical information and serum and tissue samples from children with biliary atresia (BA) and idiopathic neonatal hepatitis (INH) to facilitate research and to perform clinical, epidemiological and therapeutic trials in these two important pediatric liver diseases.
The American Liver Foundation
The American Liver Foundation recognizes that parents of children with biliary atresia need help in coping with the immense strain of this chronic illness. This organization coordinates mutual help groups through its chapters to provide emotional support for families and keeping people aware of the latest research developments. Information on local chapters can be found on this foundation's website.
800-GO-Liver (800-465-4837) toll-free - http://www.liverfoundation.org
Children's Liver Association for Support Services (C.L.A.S.S.)
The Children's Liver Association for Support Services is an all-volunteer, nonprofit organization dedicated to serving the emotional, educational, and financial needs of families coping with childhood liver disease and transplantation.
877-679-8256 (toll-free) - http://www.classkids.org