ColorDoppler images of umbilical cord vessels

(A) Normal three-vessel umbilical cord. Color Doppler shows presence of two umbilical arteries, one on each side of the bladder.
(B) Two-vessel umbilical cord. Color Doppler images show alternating single artery and vein.
(C) Two-vessel umbilical cord. Transverse view at the level of the fetal bladder shows an artery on only one side of the fetal bladder.