Biliary atresia is congenital disorder characterized by the absence or paucity of the extrahepatic biliary tree.

On ultrasound, the triangular cord sign refers to echogenic fibrous tissue adjacent to the portal vein, representing the abnormal bile duct. The gallbladder is absent in half of cases.

Early surgical intervention with Kasai procedure reduces the need for transplantation. Biliary atresia is the most common indication for liver transplantation in children. 

This child developed cirrhosis despite Kasai procedure and required a liver transplant at age 1.