The intrahepatic biliary duct is a tube that is inside the liver and transports bile in the liver. Dilatation is the expansion or widening of the duct. Dilatation of the bile duct can be due to several causes including obstruction (blockage) of the bile duct, presence of a cyst or mass in the bile duct, benign (non-cancerous) strictures or infection. Symptoms, if present, could include right upper quadrant pain and/or jaundice.