Question:medium
Where is the highest oxygen concentration present in fetal circulation?
Where is the highest oxygen concentration present in fetal circulation?
Show Hint
Follow the route of umbilical vein blood after it leaves the placenta.
Updated On: Jun 23, 2026
- Superior vena cava (SVC)
- Inferior vena cava (IVC)
- Right ventricle
- Aorta
Show Solution
The Correct Option is B
Solution and Explanation
Clinical pearl: in the fetus the placenta does the breathing, so the vessel closest to the placental return carries the highest oxygen. Oxygen-rich blood exits the placenta via the umbilical vein, bypasses the liver through the ductus venosus, and dumps straight into the inferior vena cava. That makes the IVC the most oxygenated large vessel, so option (b) is correct.
Eliminate the rest quickly: the SVC carries used blood back from the brain and arms, so it is poorly oxygenated. The right ventricle gets a blend that already includes SVC blood. The aorta is fed downstream after mixing across the ductus arteriosus, lowering its saturation further. Highest oxygen content tracks the IVC because it sits right at the receiving end of the umbilical/ductus venosus stream.
Ref: Nelson Textbook of Pediatrics, 20e.
Eliminate the rest quickly: the SVC carries used blood back from the brain and arms, so it is poorly oxygenated. The right ventricle gets a blend that already includes SVC blood. The aorta is fed downstream after mixing across the ductus arteriosus, lowering its saturation further. Highest oxygen content tracks the IVC because it sits right at the receiving end of the umbilical/ductus venosus stream.
Ref: Nelson Textbook of Pediatrics, 20e.
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