Your liver makes a substance called bile that helps with digestion. Your gallbladder stores it until you need it to digest fat. Then your gallbladder pushes the bile into tubes called bile ducts. They carry the bile to your small intestine. Different diseases can block the bile ducts and cause a problem with the flow of bile. Gallstones are one of the most common causes of blocked bile ducts. Blocked bile ducts may also result from infection, cancer or to internal scar tissue. Scarring can block the bile ducts, which can lead to liver failure. A rare form of bile duct disease called biliary atresia occurs in infants. It is the most common reason for liver transplants in children in the United States.