Biliary atresia

Atresia refers to the obstruction or absence of a lumen or passageway, biliary has to do with the bile, bile ducts, or gallbladder, so biliary atresia is when there’s some sort of blockage, deformity, or even total absence of a bile duct.

Biliary atresia specifically refers to newborns or young infants, and it can be a congenital defect, meaning something that happens during fetal development, but more commonly it’s some sort of inflammation that happens soon after birth that leads to destruction of the bile ducts.

There isn’t a definitive cause of biliary atresia; but it’s generally thought that some viral or toxic substance might induce the inflammation, Some genetic mutations have also been suggested—like a mutation in the CFC1 gene which is involved in development of the left-right embryonic axis.

Mutations with this gene have been linked to other congenital defects as well. At any rate, the mechanisms and pathogenesis are still pretty foggy, and it likely depends on a combinations of genetic and environmental factors.

Newborns with biliary atresia usually develop jaundice. Since there’s some destruction or deformity of the bile ducts, eventually there’s an obstruction to bile flow right?

And bile will start to build up, pressure in the ducts will increase and the bile will eventually push its way through the tight junctions between epithelial cells lining the ducts and leak out into the blood.

This increases the amount of conjugated bilirubin in the blood which leads to the yellowing of skin and eyes. Although not the most common cause of neonatal jaundice overall, it is the most common cause of neonatal jaundice that’s surgically treatable, and early recognition of the disease improves the effectiveness of surgery.

Typically, the surgical procedure used for biliary atresia is called the Kasai procedure, and basically what’s done is the damaged bile ducts outside the liver are first removed, and then the small intestine is cut and one end is directly reattached to the liver where the bile flows out of it, where the bile ducts used to be.

This allows the bile to drain directly into the small intestine. The other end of the small intestine is reattached to another spot along the small intestines, such that now there’s both a path from the stomach to the small intestine, as well as a path for bile to drain from the liver.

Although this procedure can be effective at reestablishing some bile flow, a lot of newborns continue to have slowly progressing liver disease, and will often need a liver transplant by two years of age.