The two umbilical arteries carry the \ \ \ \ \ \ \ \ \ \ \ \ from the fetus. - KGMU 2024

KGMU 2024

Obstetrics & Gynaecology

Easy

Appeared in: KGMU 2024

Explanation

The two umbilical arteries are responsible for transporting deoxygenated blood and metabolic waste products away from the fetus.
This blood travels from the fetus to the placenta, where it releases carbon dioxide and waste products and picks up oxygen and nutrients.
This is a unique and critical feature of fetal circulation, where arteries carry deoxygenated blood, which is the opposite of the role of arteries in adult systemic circulation.
The now-oxygenated blood returns to the fetus through the single umbilical vein.

Option A: Oxygenated blood is carried from the placenta to the fetus, not from the fetus.
Option C: While blood mixing occurs at various points in the fetal circulatory system (e.g., ductus venosus, foramen ovale), the blood within the umbilical arteries is specifically deoxygenated blood being returned to the placenta for gas exchange.
Option D: The umbilical cord is the fetus's lifeline and is composed of blood vessels that are actively transporting blood to and from the placenta.

Visual 1: Diagram - A clear diagram of fetal circulation. It should illustrate the placenta, the umbilical cord with two arteries and one vein, and the fetus. Arrows should indicate the direction of blood flow, and colors should differentiate between oxygenated blood (red) in the umbilical vein and deoxygenated blood (blue) in the umbilical arteries.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Fetal circulation and the function of umbilical cord vessels as background academic context rather than a clinical decision trigger.
At birth, the umbilical cord is clamped and cut, but its assessment is crucial. A nurse or doctor will check for the presence of two arteries and one vein (AVA). The absence of one umbilical artery (a two-vessel cord or single umbilical artery - SUA) can be associated with other congenital anomalies, particularly of the kidneys or heart.
What if? - If a newborn has a single umbilical artery (SUA), the standard of care involves a thorough physical examination to look for any associated anomalies. Further investigations, like a renal ultrasound, may be ordered depending on the clinical findings, although many infants with an isolated SUA are perfectly healthy.
Umbilical artery blood gas analysis is a common test performed immediately after birth, especially in high-risk deliveries. The pH and gas levels in the umbilical artery blood provide an objective measure of the baby's metabolic state just before delivery and can help assess for fetal distress.

How to Approach the Question

First, identify the key terms in the question: 'two umbilical arteries' and 'from the fetus'.
Recall the basic principles of fetal circulation, noting that it differs significantly from adult circulation.
Focus on the direction of flow. The question asks what is carried from the fetus, which means blood is flowing away from the baby and towards the placenta.
Remember the key exception to the artery/vein rule in this context: Umbilical arteries carry deoxygenated blood away from the fetus, while the umbilical vein carries oxygenated blood to the fetus.
Evaluate the options based on this knowledge. 'Deoxygenated blood' correctly describes the blood flowing from the fetus to the placenta via the arteries.
Eliminate the incorrect options: 'Oxygenated blood' is carried by the vein to the fetus. 'Mixed blood' is too general. 'No blood' is illogical.

Concept Tested & Keywords

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