Which vessel carries deoxygenated blood from the fetus to the placenta?

• A. Umbilical vein
• B. Ductus venosus
• C. Umbilical artery
• D. Foramen ovale

Answer: (C)

In fetal circulation, gas exchange happens in the placenta, and the blood that goes to the placenta from the fetus is deoxygenated. That task is carried out by the umbilical arteries, which transport blood away from the fetus toward the placenta. The umbilical vein, by contrast, brings oxygenated blood from the placenta back to the fetus. The ductus venosus is a shunt that helps blood bypass the liver, and the foramen ovale is an opening between the atria—neither is a vessel delivering blood to the placenta. So the vessel that carries deoxygenated blood from the fetus to the placenta is the umbilical arteries.