A 26-year-old woman presents at 34 weeks gestational age with dizziness and shortness of breath when lying on her back. In the office, her blood pressure is 124/76 while standing and sitting, but drops to 88/50 when the patient is supine. Which of the following is most likely to explain these findings?
Compression of the inferior vena cava by the gravid uterus
Dehydration due to hyperemesis gravidum
Hemorrhage from placental abruption
Hyperventilation due to anxiety about her labor and delivery
Pulmonary embolism from hypercoaguable state and venous stasis
Correct answer
Compression of the inferior vena cava by the gravid uterus
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correct answer: A
The correct answer is Compression of the IVC by the gravid uterus. This is known as IVC syndrome and is a common cause for decreased supine blood pressure in the third trimester. Women are counseled to sleep on their side to improve symptoms. The other choices can all occur during pregnancy. However, given the decrease in supine blood pressure only, compression of the IVC is the best answer.
Dehydration due to hyperemesis gravidum often resolves prior to the 3rd trimester. If the woman was dehydrated secondary to vomiting, she likely would have decreased blood pressure upon standing and sitting.
Placental abruption often presents with painful contractions and bleeding. The woman would not present with an isolated finding of decreased BP when supine.
Hyperventilation due to anxiety may cause the woman to feel lightheaded and short of breath, but there is no history of anxiety given and this does not explain the decreased BP when supine.
Pulmonary embolism from the hypercoaguable state of pregnancy likely would present with other symptoms of tachycardia and shortness of breath upon standing. While pregnancy is a hypercoaguable state, it is unlikely that a PE would cause isolated decreased BP when supine.