In fetal circulation, which structure allows oxygenated blood from the umbilical vein to bypass the liver and enter the inferior vena cava?

In fetal circulation, which structure allows oxygenated blood from the umbilical vein to bypass the liver and enter the inferior vena cava?

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

Answer: (A)

During fetal life, oxygen-rich blood from the placenta travels through the umbilical vein. The ductus venosus acts as a direct shortcut, channeling this blood into the inferior vena cava and bypassing the liver. This arrangement ensures that highly oxygenated blood reaches the heart and systemic circulation efficiently. The other structures have different roles: the foramen ovale shunts blood from right to left atrium to bypass the fetal lungs; the ductus arteriosus connects the pulmonary artery to the aorta to bypass the lungs; the umbilical arteries carry blood from the fetus to the placenta. After birth, the ductus venosus normally closes, and liver circulation resumes its usual route.

During fetal life, oxygen-rich blood from the placenta travels through the umbilical vein. The ductus venosus acts as a direct shortcut, channeling this blood into the inferior vena cava and bypassing the liver. This arrangement ensures that highly oxygenated blood reaches the heart and systemic circulation efficiently. The other structures have different roles: the foramen ovale shunts blood from right to left atrium to bypass the fetal lungs; the ductus arteriosus connects the pulmonary artery to the aorta to bypass the lungs; the umbilical arteries carry blood from the fetus to the placenta. After birth, the ductus venosus normally closes, and liver circulation resumes its usual route.