The triangular cord sign is a triangular or tubular echogenic cord of fibrous tissue, representing the ductal remnant of the extrahepatic bile duct, seen in the porta hepatis at ultrasonography, and is relatively specific for the diagnosis of biliary atresia 1,2.
This sign is useful in the evaluation of infants with cholestatic jaundice, helping in the differential diagnosis of biliary atresia from neonatal hepatitis.
It is defined as more than 4 mm thickness of the echogenic anterior wall of the right portal vein (EARPV) measured on a longitudinal ultrasound scan 2.