Umbilical Cord Anatomy at Term

The umbilical cord is a crucial structure connecting the developing fetus to the mother's placenta during pregnancy. It acts as the primary pathway for the exchange of essential substances, including nutrients, oxygen, and waste products, ensuring the healthy growth and development of the baby.

Umbilical Cord Composition

At full term, a typical human umbilical cord contains a specific and vital arrangement of blood vessels. This particular composition is fundamental for maintaining the efficient fetal circulation. The standard and healthy composition of the umbilical cord includes:

• Two umbilical arteries: These arteries are responsible for carrying deoxygenated blood and metabolic waste products away from the fetus and back to the placenta. The blood within these arteries is rich in carbon dioxide and other waste materials generated by the fetal metabolism.
• One umbilical vein: This single vein plays the role of transporting oxygenated blood and nutrient-rich blood from the placenta directly to the fetus. The blood in this vein is highly oxygenated and contains all the necessary nutrients required for the fetal growth and development.

These crucial blood vessels are surrounded by a protective, gelatinous substance known as Wharton's jelly. This jelly helps prevent the compression of the vessels, ensuring a continuous and uninterrupted flow of blood. The entire umbilical cord structure is further encased by an outer layer of amniotic epithelium.

Function of Umbilical Arteries and Umbilical Vein

The distinct and specialized roles of the umbilical arteries and the single umbilical vein are critical for the survival and proper development of the fetus:

• Umbilical Arteries (Two):
  • Origin: These two arteries branch directly from the internal iliac arteries within the fetal circulatory system.
  • Function: Their primary function is to transport deoxygenated blood and various metabolic waste products (such as carbon dioxide and urea) from the fetal body to the placenta. Once at the placenta, these waste products are efficiently transferred into the maternal blood circulation for excretion by the mother's body.
  • Blood Type Carried: Deoxygenated blood.
• Umbilical Vein (One):
  • Origin: This vein originates from the placenta and carries blood towards the fetal liver, where it often connects to the ductus venosus, a shunt that allows blood to bypass the liver.
  • Function: The main function of the umbilical vein is to deliver oxygen-rich, nutrient-laden blood from the placenta to the fetal circulatory system. This continuous supply provides all the necessary oxygen and nourishment for the rapid growth and development of the fetus.
  • Blood Type Carried: Oxygenated blood.

This specific arrangement, consisting of two umbilical arteries and one umbilical vein, is the standard and healthy configuration observed in a full-term pregnancy, effectively supporting the physiological needs of the developing baby.