First visualized at 8 weeks as a straight thick structure, when diameter <2 centimeters.
Umbilical artery arises from fetal internal iliac artery. In newborn, it becomes the superior vesical artery and the medial umbilical ligament.
Umbilical vein carries oxygenated blood from the placenta to the fetus through ductus venosus into IVC and to the heart.
Single left umbilical vein becomes ligamentum teres and attaches to the left portal vein.
Ductus venosus becomes the ligamentum venosum in newborns.
Allantois is associated with bladder development, becomes urachus and median umbilical ligament.
Yolk stalk connects the primitive gut to yolk sac. The paired vitelline vessels follow the stalk to provide blood supply to the yolk sac.
Cord normally inserts in the central portion of the placenta. May insert marginally and paramarginally.
Velamentous insertion—Insertion of cord beyond the edge into the free membrane.