Which statement is correct regarding fetal circulation?

NORCET-7 Mains-2024

Obstetrics & Gynaecology

Easy

Appeared in: NORCET-7 Mains-2024

Explanation

The umbilical cord normally contains three vessels: two umbilical arteries and one umbilical vein.
The single umbilical vein carries oxygenated, nutrient-rich blood from the placenta to the fetus.
The two umbilical arteries carry deoxygenated blood and waste products away from the fetus to the placenta.
This configuration is often remembered by the mnemonic 'AVA' (Artery-Vein-Artery).

Option A: This statement is incorrect because the umbilical arteries carry deoxygenated blood away from the fetus to the placenta for re-oxygenation.
Option C: This statement is incorrect because the umbilical vein carries oxygenated and nutrient-rich blood from the placenta to the fetus.
Option D: This statement incorrectly reverses the number of vessels. The correct anatomy is two arteries and one vein.

Visual 1: Diagram - A clear diagram of fetal circulation, highlighting the placenta, umbilical cord with two arteries and one vein, and the direction of blood flow. Color-coding oxygenated (red) and deoxygenated (blue) blood would be essential.
Visual 2: Illustration - A cross-section of the umbilical cord showing the two smaller, thicker-walled arteries and the single larger, thinner-walled vein, often with a 'smiley face' appearance.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Fetal circulation and umbilical cord anatomy as background academic context rather than a clinical decision trigger.
Nurses and midwives routinely inspect the umbilical cord at birth to confirm the presence of three vessels (two arteries, one vein). This is a standard part of the newborn assessment.
The absence of one umbilical artery, known as a Single Umbilical Artery (SUA) or a 'two-vessel cord,' is a common congenital malformation.
While many infants with a SUA are healthy, its presence can be a soft marker for other underlying congenital anomalies, particularly of the renal (kidney) and cardiovascular (heart) systems. Further evaluation may be warranted.

How to Approach the Question

This is a factual recall question testing knowledge of fundamental anatomy and physiology.
First, identify the core concept being tested: the structure and function of the umbilical cord in fetal circulation.
Recall the standard anatomy of the umbilical cord. A helpful mnemonic is 'AVA' for Artery-Vein-Artery, indicating two arteries and one vein.
Next, recall the function of these vessels. Remember that arteries in fetal circulation carry blood 'Away' from the fetus (deoxygenated), while the vein carries blood to the fetus (oxygenated). This is the opposite of adult circulation.
Evaluate each option against these two key facts: the number of vessels and the type of blood they carry.
Option A incorrectly states arteries carry oxygenated blood. Option C incorrectly states the vein carries deoxygenated blood. Option D has the wrong number of vessels. Option B correctly states there are two arteries and one vein.

Concept Tested & Keywords

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