NCC Certified Electronic Fetal Monitoring (C-EFM) Practice Exam

Which structure in the fetal circulation is responsible for carrying the most highly oxygenated blood?

1. Ductus Venosus

2. Umbilical Artery

3. Foramen Ovale

4. Inferior Vena Cava

The correct answer is: Ductus Venosus

The structure in the fetal circulation responsible for carrying the most highly oxygenated blood is the ductus venosus. This vessel serves a critical role in directing oxygen-rich blood from the placenta to the fetus. The umbilical vein brings oxygenated blood from the placenta to the fetus, and a significant portion of this blood passes through the ductus venosus, which allows it to bypass the liver and enter the inferior vena cava directly. Consequently, the blood that reaches the heart via the inferior vena cava is more oxygenated than the blood that returns from the lower portions of the fetus’s body. While the foramen ovale plays an important role in shunting blood between the atria of the heart, it is the ductus venosus that ensures the most oxygenated blood is sent to the major circulation quickly and efficiently. The umbilical artery, on the other hand, carries deoxygenated blood from the fetus back to the placenta, while the inferior vena cava collects blood returning from the lower body, which contains less oxygen than that passing through the ductus venosus. These distinctions highlight why the ductus venosus is critical for supplying the fetus with the highest concentration of oxygenated blood.