In the flow of fetal circulation, which vessel carries oxygenated blood from the placenta to the fetus?

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

Answer: (A)

In fetal circulation, the placenta is the place of gas exchange, and the oxygenated blood returns to the fetus through the umbilical vein. This vessel carries blood rich in oxygen from placenta to the fetal circulation, traveling via the umbilical cord toward the abdomen and heart. From there, some of this blood is shunted through the ductus venosus on its way to the heart, but the vessel that brings oxygenated blood from placenta to fetus is the umbilical vein. The umbilical artery carries blood in the opposite direction—from fetus to placenta and is not the conduit for placental blood to the fetus. The foramen ovale is an atrial opening that allows blood to pass between the right and left atria, not a vessel carrying placental blood. The ductus venosus is a fetal shunt that helps direct oxygenated blood toward the heart, but it is not the vessel connecting placenta to fetus.