Single umbilical artery as depicted by three-dimensional angiography

Three-dimensional angiosonogram demonstrating the umbilical vessels in a free loop of the cord.

(Panel A) Normal three-vessel cord. Two arteries (A) are looping around the vein (V).

(Panel B) Two vessels in a relatively straight umbilical cord. One artery and one vein are seen in the axial and longitudinal views.