Compression effect of gravid uterus on the inferior vena cava results in?

Daman & Diu Staff Nurse - 2018

Obstetrics & Gynaecology

Hard

Appeared in: Daman & Diu Staff Nurse - 2018

Explanation

In late pregnancy, the weight of the gravid uterus can compress the inferior vena cava (IVC) when the woman is in a supine position.
This compression reduces venous return to the heart, which is the amount of blood flowing back from the body.
A decrease in venous return leads to a reduction in cardiac output (the amount of blood the heart pumps per minute).
The fall in cardiac output causes a significant drop in systemic blood pressure, known as supine hypotension.
This condition is also called Aortocaval Compression Syndrome and is characterized by symptoms like dizziness, pallor, and nausea.
The immediate intervention is to turn the patient to her left lateral position to relieve the pressure on the IVC.

Option A: Carpal tunnel syndrome is caused by compression of the median nerve in the wrist, typically due to increased fluid retention during pregnancy, not by compression of the inferior vena cava.
Option B: Supine hypertension is the opposite of what occurs. Compression of the IVC decreases venous return and cardiac output, leading to a fall in blood pressure (hypotension), not an increase.
Option D: HELLP syndrome is a severe variant of preeclampsia, characterized by Hemolysis, Elevated Liver enzymes, and Low Platelets. Its pathophysiology is related to systemic endothelial dysfunction, not mechanical compression of the IVC.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Supine Hypotensive Syndrome (Aortocaval Compression) in Pregnancy as background academic context rather than a clinical decision trigger.
Nurses must educate pregnant women, especially after 20 weeks of gestation, to avoid lying flat on their backs for extended periods.
The recommended position for rest and sleep is the left lateral position to promote optimal venous return and placental perfusion.
During labor, especially if an epidural is in place (which can also cause hypotension), maintaining a lateral tilt is crucial to prevent supine hypotensive syndrome and ensure fetal well-being.

How to Approach the Question

First, identify the key elements in the question: a gravid (pregnant) uterus, the inferior vena cava (IVC), and a compression effect.
Recall the function of the IVC: it returns deoxygenated blood from the lower body to the heart.
Consider the hemodynamic consequences of compressing this major vein. Compression will reduce blood flow back to the heart.
Trace the physiological cascade: Reduced blood return (preload) leads to reduced cardiac output, which in turn causes a drop in blood pressure (hypotension).
Evaluate the options based on this physiological understanding. 'Supine hypotension' directly matches the consequence of this compression when lying supine.
Rule out the other options by recalling their distinct causes: Carpal tunnel (nerve compression), Supine hypertension (physiologically incorrect), and HELLP syndrome (a variant of preeclampsia).

Concept Tested & Keywords

Concept Tested: Supine Hypotensive Syndrome (Aortocaval Compression) in Pregnancy
Stem keywords: gravid uterus, inferior vena cava, compression effect
Lead-in keywords: results in