Supine Hypotensive Syndrome (Aortocaval Compression Syndrome)
Supine hypotensive syndrome occurs due to compression of the abdominal aorta and inferior vena cava by the gravid uterus when a pregnant woman lies flat on her back (supine position). This compression reduces venous return to the heart, leading to maternal hypotension (low blood pressure).
It is a common cause of hypotension during late pregnancy and may result in dizziness, fainting (syncope), or loss of consciousness. In severe and untreated cases, reduced uteroplacental blood flow may compromise fetal oxygenation and, in rare extreme circumstances, may lead to fetal distress or fetal demise.
This condition can be prevented by left lateral positioning or elevating the right hip by approximately 10–12 cm, which shifts the uterus away from the major blood vessels and relieves compression.
Signs and Symptoms:
- Syncope (fainting)
- Restlessness
- Dizziness
- Headache and tinnitus
- Visual disturbances
- Numbness or paresthesia of the limbs
- Pallor
- Sweating
- Nausea
- Hypotension
- Tachycardia
Note that it is more common in third trimester pregnancy
Pathophysiology
- Uterus presses on major blood vessels
- Reduced venous return to heart
- Decreased cardiac output
- Maternal hypotension develops
- Reduced uteroplacental perfusion may affect fetal well-being
Complications
Maternal:
- Severe hypotension
- Loss of consciousness
- Reduced organ perfusion
- Shock (rare)
Fetal:
- Fetal distress
- Reduced oxygenation
- Bradycardia
- In rare severe untreated cases, fetal demise
Prevention
- Avoid lying flat on the back in late pregnancy
- Prefer left lateral position (best position)
- Place a pillow/wedge under the right hip (10–12 cm elevation)
- During dental/medical procedures, tilt patient slightly to left
Management
- Turn patient to left lateral recumbent position
- Oxygen support if required
- Monitor maternal BP and fetal heart rate
- IV fluids if severe hypotension
- Immediate medical attention if unconsciousness occurs
Did you know a small change in position can protect both mother and fetus during late pregnancy?