Umbilical artery


The umbilical artery is a paired artery that is found in the abdominal and pelvic regions. In the fetus, it extends into the umbilical cord.

Structure

Development

The umbilical arteries supply systemic arterial blood from the fetus to the placenta. Umbilical artery blood is enriched in CO2 and deoxygenated in comparison with other fetal blood. There are usually two umbilical arteries present together with one umbilical vein in the umbilical cord. The umbilical arteries surround the urinary bladder and then carry all the deoxygenated blood out of the fetus through the umbilical cord. Inside the placenta, the umbilical arteries connect with each other at a distance of approximately 5 mm from the cord insertion in what is called the Hyrtl anastomosis. Subsequently, they branch into chorionic arteries or intraplacental fetal arteries.
The umbilical arteries are actually the anterior division of the internal iliac arteries, and retain part of this function after birth.
The umbilical arteries are one of two arteries in the human body that carry deoxygenated blood, the other being the pulmonary arteries.
The pressure inside the umbilical artery is approximately 50 mmHg. Resistance to blood flow decreases during development as the artery grows wider.

After development

The umbilical artery regresses after birth. A portion obliterates to become the medial umbilical ligament. A portion remains open as a branch of the anterior division of the internal iliac artery. The umbilical artery is found in the pelvis, and gives rise to the superior vesical arteries, which in males usually supplies the artery to the ductus deferens. Alternately, the latter artery can be supplied by the inferior vesical artery in some individuals.

Clinical significance

A catheter may be inserted into one of the umbilical arteries of critically ill babies for drawing blood for testing. This is a common procedure in neonatal intensive care, and can often be performed until 2 weeks after birth. The umbilical arteries are typically not suitable for infusions.