Occurs when the gravid uterus compresses the maternal abdominal aorta and inferior vena cava
Pathophysiology
From 20 weeks gestation, in the supine position, the gravid uterus can compress IVC and aorta, reducing venous return
This decreases cardiac output by up to 40%, causing supine hypotension
Supine hypotension can precipitate maternal collapse, which is usually reversed by turning the woman into the left lateral position
Clinical features
Aortocaval compression is thought to be the cause of supine hypotensive syndrome - characterized by pallor, tachycardia, sweating, nausea, hypotension and dizziness which occurs when a pregnant woman lies on her back and resolves when she is turned on her side
Investigations
Clinical diagnosis
Management
Keep mother supine and apply left manual uterine displacement or 30-degree tilt if on theatre table
As soon as infant is delivered, vena cava returns to normal and cardiac output is restored