Aortocaval compression syndrome is compression of the abdominal aorta and inferior vena cava by the gravid uterus when a pregnant woman lies on her back, i.e. in the supine position. It is a frequent cause of low maternal blood pressure (hypotension), which can in result in loss of consciousness and in extreme circumstances fetal demise.
Aortocaval compression is thought to be the cause of supine hypotensive syndrome. Supine hypotensive syndrome is characterized by pallor, bradycardia, sweating, nausea, hypotension and dizziness and occurs when a pregnant woman lies on her back and resolves when she is turned on her side.
The aorta and inferior vena cava are central vessels, the largest artery and vein. They supply blood to the heart, and the rest of the body. Thus, when there is compression due to the weight of the fetus, signs of shock (sweating, pallor, fast and weak pulse) may be experienced. Patients should be placed in a left lateral recumbent and emergency help summoned immediately.