Oxygenated blood enter the fetal circulation from umbilical vein via

Appeared in: JIPMER Nursing Officer-2017

Explanation

In fetal life, the umbilical vein carries oxygen-rich blood from the placenta.
The ductus venosus is a crucial fetal shunt that connects the umbilical vein directly to the inferior vena cava.
This connection allows a significant portion of the highly oxygenated blood to bypass the fetal liver's circulation.
Bypassing the liver ensures that the most oxygenated blood is delivered efficiently to the fetal heart, brain, and upper body.

Option B: The ductus arteriosus is a different fetal shunt that connects the pulmonary artery to the aorta.
Option C: While some blood from the umbilical vein does enter the liver sinusoids and drain via hepatic veins, this is not the primary pathway for oxygenated blood to enter the main fetal circulation.
Option D: The intrahepatic artery supplies arterial blood to the liver tissue itself; it does not receive blood from the umbilical vein.

Clinical Relevance

Nursing practice connection: Knowing Fetal Circulation Pathways helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding fetal circulation is critical for assessing the transition to neonatal circulation at birth. The closure of these shunts is a key physiological event.
Failure of the ductus venosus to close after birth results in a patent ductus venosus (PDV), a rare condition where portal blood continues to shunt into the systemic circulation, bypassing the liver. This can lead to complications like hyperammonemia and hepatic dysfunction.
What if? If the ductus venosus failed to develop, all placental blood would have to pass through the liver sinusoids. This would significantly reduce the oxygen saturation of the blood reaching the fetal brain and heart, potentially leading to severe developmental issues or fetal distress.

How to Approach the Question

First, identify the core concept of the question, which is the pathway of blood in the fetus.
Recall the source of oxygenated blood for the fetus, which is the placenta, delivered via the umbilical vein.
Remember that the fetal lungs and liver are not fully functional and have shunts to bypass them.
Differentiate between the three main fetal shunts: ductus venosus (bypasses liver), foramen ovale (bypasses right ventricle/lungs), and ductus arteriosus (bypasses lungs).
Connect the umbilical vein to the shunt that bypasses the liver, which is the ductus venosus, to determine the correct answer.

Concept Tested & Keywords

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E6 Anatomy Grays 43e Vol 1 Part 2 pp. 54-56, 57-59

E6 Obstetrics Williams p. 22-41

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