Question

What does the umbilical artery do?

• A. Carrying deoxygenated blood from fetus to placenta
• B. Carrying oxygenated blood from placenta to fetus
• C. Provide nutrients
• D. None of the above

Hint:

Remember that in fetal circulation, arteries carry blood away from the fetal heart -- regardless of oxygen content.

Answer 1

The Correct Option is A

Step 1: Recall the structure of the umbilical cord. The umbilical cord contains three vessels: two umbilical arteries and one umbilical vein.

Step 2: Understand fetal circulation conventions. In fetal circulation, the terms artery and vein are defined by direction of blood flow relative to the fetal heart -- not by oxygenation status (unlike postnatal circulation).

• Umbilical arteries (x2): Carry deoxygenated, waste-laden blood FROM the fetus TO the placenta for oxygenation and nutrient exchange. They arise from the internal iliac arteries of the fetus.
• Umbilical vein (x1): Carries oxygenated, nutrient-rich blood FROM the placenta TO the fetus. It enters the liver and also connects to the inferior vena cava via the ductus venosus.

Step 3: Additional anatomical fact. The two umbilical arteries converge approximately 5 mm from the cord insertion, forming a vascular anastomosis called the Hyrtl anastomosis, which helps equalize pressure between the two arteries.

Conclusion: The umbilical artery carries deoxygenated blood from the fetus to the placenta.