What does the ductus venosus connect in fetal circulation?

• A. The umbilical artery to the aorta
• B. The umbilical vein to the inferior vena cava
• C. The placental blood vessel to the heart
• D. The inferior vena cava to the superior vena cava

Answer: (B)

In fetal circulation, the ductus venosus plays a crucial role by connecting the umbilical vein to the inferior vena cava. This connection allows oxygen-rich blood from the placenta to bypass the liver and directly enter the systemic circulation, which is essential for efficiently delivering oxygen and nutrients to the developing fetus.

The umbilical vein carries this oxygenated blood from the placenta to the fetus, and by flowing through the ductus venosus, this blood is directed towards the inferior vena cava. From there, it travels to the right atrium of the heart. The ductus venosus is a vital structure for maintaining adequate blood flow and oxygenation during fetal development, allowing the fetus to utilize the well-oxygenated blood from the placenta while minimizing the workload on the liver, which is not fully functional in the womb.

The other options describe connections that do not occur in the fetal circulatory system. For instance, the umbilical artery does not connect to the aorta through the ductus venosus, and while placental blood vessels do connect to the heart, this connection is not made through the ductus venosus. Neither is there a connection from the inferior vena cava to the superior vena cava through this structure