Version July 2025
(A,D) Single umbilical artery. Transverse section of a two-vessel umbilical cord in two different fetuses shows the typical "soda can tab" sign.
(B,E) Single umbilical artery. Longitudinal views of a two-vessel umbilical cord as depicted by two-dimensional ultrasound show the single umbilical artery (SUA) and the vein (V). Image B shows fetus with a straight, noncoiled umbilical cord. Image E shows fetus with a coiled umbilical cord.
(C,F) Single umbilical artery. Color Doppler ultrasound shows a straight, noncoiled, two-vessel umbilical cord (C) and a coiled two-vessel umbilical cord (F).