Aortocaval Compression

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 presentation

  • 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