Biliary atresia is a rare disease of extrahepatic bile duct obstruction that leads to end-stage liver disease in children. The obstruction of bile duct leads to the accumulation of bile in the liver itself giving rise to inflammatory process in the liver that finally leads to liver damage. It is the most common cause of cholestasis in neonates and also the most common cause of liver transplantation in children. Biliary atresia is more common in people of Asian or African-American descent with a slightly more female predilection.
It can be congenital known as fetal (embryonic) biliary atresia that is present at the time of birth and may or may not be related to other congenital anomalies. The other type is acquired, also known as perinatal biliary atresia, which is mostly seen 2 to 4 weeks after the birth of the neonate with the first sign of jaundice.
Causes and Pathogenesis of Biliary Atresia
The exact cause of biliary atresia is still unknown, but there are several hypotheses regarding its onset. In some infants, there has been some evidence regarding alterations and deformity in the early development of bile duct intrauterine that could be seen in antenatal ultrasound. Congenital biliary atresia has been associated with other congenital anomalies such as polysplenia, asplenia, situs inversus, choledochal cyst and hepatic vascular inflow anomalies, which hold strong evidence that all these anomalies are a result of problems associated in the first trimester when organogenesis takes place. Genetics have also been studied regarding pathogenesis of biliary atresia that might predispose to viral infections. However, there is no strong evidence of any genetic predisposition, as it does not run in families and there have been cases where one twin is born with biliary atresia and the other born healthy.
Perinatal biliary atresia has been associated with gastrointestinal viral infections including cytomegalovirus, reovirus type 3, Epstein Barr virus, human papillomavirus and rotavirus type A. These viruses have been known to induce proinflammatory factors responsible for the damage of bile duct. Immune system dysfunction has also been postulated as a cause for biliary atresia. All these studies need further validation to prove the right pathogenesis for biliary atresia.
Can Biliary Atresia Be Prevented?
Biliary atresia is a fatal disease if left untreated. Since the cause of it is largely unknown, so nothing can be done to prevent the onset of the disease. If there were any definite cause for the development of biliary atresia, then one could work on preventing the cause, but there is no definitive cause, just hypothesis, so nothing can be done to prevent the disease once if affects a child. However, one can always prevent the progression of the disease and ensuing complications by early diagnosis and treatment. Biliary atresia and fibrosis related to it is a rapidly progressing condition, so it is necessary to take prompt treatment for it before it is too late and the complications associated with it cannot be prevented. The treatment should be done as early as possible, usually before the infant is 3 months old to get better postoperative results. Kasai procedure helps children to grow and remain in good health for several years.
The only effective management of biliary atresia is Kasai procedure that involves removal of the obliterated extrahepatic bile duct and re-establishing the connection between liver and small intestine by connecting a segment of small intestine directly with the liver. This procedure helps regain bile drainage in about 80% cases. There is normalization of bilirubin level within 3 months postoperatively, whereas the stool color also comes back to normal within first postoperative week. The most common complications of surgery include cholangitis and portal hypertension.
There are high numbers of cases around 20 to 25% where Kasai procedure is not successful, the bile flow is not restored after which life threatening complications of fibrosis and cirrhosis develops that mandate liver transplantation. The five-year survival rate with native liver is 40 to 65%, whereas, three-year survival rate with liver transplantation is about 85 to 90%.