What structure is compressed in a pregnant patient developing hypotension after lying supine for 2 minutes?

• A. Aorta
• B. Inferior vena cava
• C. Common iliac artery
• D. Descending aorta

Answer: (B)

During pregnancy, especially in the later stages, lying supine can lead to a condition often referred to as supine hypotensive syndrome. This phenomenon occurs when the weight of the gravid uterus compresses the inferior vena cava, which is the large vein that carries deoxygenated blood from the lower half of the body back to the heart.

When the inferior vena cava is compressed, it can impede venous return, leading to decreased cardiac output and subsequently hypotension. This is particularly concerning as it can affect blood flow to the fetus and may produce symptoms in the mother such as dizziness, lightheadedness, or even fainting.

In this scenario, while the aorta and common iliac artery are significant structures within the circulatory system, they are not the ones primarily affected by this compression. The descending aorta, although it runs parallel to the inferior vena cava, typically does not experience direct compression in the same way. Thus, the correct answer is indeed the inferior vena cava, as its compression is the primary cause of hypotension in this context.