How do gallstones produce pale feces and jaundice?

Duct Blockage: Gallstones can cause pale stools and jaundice when they block ducts leading from the gallbladder and liver to the small intestine. Bile is largely responsible for the brown color of feces. Bile duct obstruction prevents bile from entering the small intestine. When the duct from the liver are blocked, bilirubin can't be secreted so it backs up into the blood stream leading to jaundice.