Medical Emergencies · single question
A pregnant patient in the THIRD TRIMESTER starts feeling dizzy and lightheaded while sitting in the dental chair. Why?
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Correct answer: C. Compression of the inferior vena cava and aorta (aortocaval compression)
Aortocaval compression (C) — also called supine hypotensive syndrome. In the third trimester, the enlarged uterus compresses the inferior vena cava and aorta when the patient is supine/reclined. This reduces venous return to the heart, decreasing cardiac output and causing hypotension, dizziness, and syncope.
• Management: Position the patient on her LEFT SIDE (left lateral tilt of 15-30°) or place a wedge under the right hip to displace the uterus off the vessels. Never lay a late-term pregnant patient fully supine for prolonged periods.
• This is also why CPR in a pregnant patient requires lateral uterine displacement.
• Clinical pearl: Any pregnant patient in the third trimester who feels lightheaded in the dental chair → immediately tilt to left lateral position.
• Management: Position the patient on her LEFT SIDE (left lateral tilt of 15-30°) or place a wedge under the right hip to displace the uterus off the vessels. Never lay a late-term pregnant patient fully supine for prolonged periods.
• This is also why CPR in a pregnant patient requires lateral uterine displacement.
• Clinical pearl: Any pregnant patient in the third trimester who feels lightheaded in the dental chair → immediately tilt to left lateral position.
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