Umbilical arteries and vein
Arteriae umbilicales et vena umbilicalis
Also known as: umbilical artery, umbilical vein, ligamentum teres, medial umbilical ligament
The umbilical cord contains three vessels. The two umbilical arteries carry deoxygenated fetal blood from the internal iliac arteries to the placenta. The single umbilical vein returns oxygenated blood to the fetus.
Overview
The three vessels are cushioned in a jelly-like connective tissue (Wharton's jelly) and twist in a helix along the cord.
Umbilical arteries. These are branches of the anterior division of the internal iliac arteries. They run up beside the bladder to the umbilicus.
Umbilical vein. There were originally two umbilical veins, but the right one disappears early in development. The left umbilical vein runs from the umbilicus in the free edge of the falciform ligament to the left branch of the portal vein, and continues as the ductus venosus.
After birth. The umbilical arteries constrict within minutes, which limits fetal blood loss. Their distal parts become the medial umbilical ligaments. Their proximal parts stay open as the superior vesical arteries. The umbilical vein becomes the ligamentum teres hepatis (round ligament of the liver) in the free edge of the falciform ligament. Small paraumbilical veins run beside it and can enlarge in portal hypertension.
Function
- Carry fetal blood to and from the placenta for gas, nutrient and waste exchange.
Clinical significance
Single umbilical artery
About 1% of umbilical cords have only one umbilical artery. This is associated with kidney, heart and chromosomal abnormalities, and prompts a detailed anomaly scan.
Umbilical catheterisation and cord care
Sick newborns can be given umbilical arterial and venous catheters for blood sampling, monitoring and infusions. Delaying cord clamping for at least 30–60 seconds after birth improves the baby's iron stores. Blood gases from the cord vessels show how well oxygenated the baby was at delivery.
Recanalised umbilical vein
In portal hypertension, the umbilical vein and paraumbilical veins can reopen. They carry blood to the veins of the abdominal wall around the umbilicus, producing caput medusae.
Compiled from standard anatomy and physiology references — see the Cardiovascular System sources. For education only; not medical advice.