Preeclampsia with severe features
USMLE Step 2 CKDifficulty: easyLast updated:
A 24-year-old primigravida at 35 weeks' gestation presents with a severe headache and blurred vision. Blood pressure is 168/112 mm Hg and, on repeat measurement 15 minutes later, 170/110 mm Hg. She has 3+ proteinuria, brisk deep tendon reflexes, and right upper quadrant tenderness. She has not had a seizure. IV labetalol is given and delivery is planned.
Which of the following medications is most appropriate to prevent eclamptic seizures?
Answer and explanation
Correct answer: E. Magnesium sulfate
This patient has preeclampsia with severe features: systolic BP ≥ 160 mm Hg and/or diastolic BP ≥ 110 mm Hg confirmed on repeat measurement, plus severe headache, visual disturbances, hyperreflexia, and right upper quadrant pain. Severe-range readings are confirmed within minutes rather than after a 4-hour wait, because ACOG advises first-line antihypertensive treatment as soon as possible within 30–60 minutes of confirmed severe hypertension to reduce the risk of maternal stroke. The source lists magnesium sulfate to prevent or treat new seizures, or to prevent recurrence, as part of management. Delivery is the definitive treatment. Immediate delivery after maternal stabilization is indicated for preeclampsia with severe features at ≥ 34 weeks. Antihypertensives such as labetalol or hydralazine lower blood pressure in severe hypertension but do not prevent eclampsia. Standard antiseizure drugs are not the agents of choice for eclampsia prophylaxis.
Each option explained
- A. LorazepamIncorrect. Benzodiazepines may be used for status epilepticus but are not used for eclampsia prophylaxis.
- B. LevetiracetamIncorrect. Levetiracetam is not the recommended prophylaxis for eclampsia.
- C. HydralazineIncorrect. Hydralazine treats severe hypertension but does not prevent seizures.
- D. PhenytoinIncorrect. Phenytoin is not the preferred agent for preventing eclamptic seizures; magnesium sulfate is.
- E. Magnesium sulfateCorrect. Magnesium sulfate is used to prevent and treat eclamptic seizures in preeclampsia with severe features.
Key point
In preeclampsia with severe features, give magnesium sulfate for seizure prophylaxis, control severe hypertension, and plan delivery.
From the source
“Magnesium sulfate to prevent or treat new seizures or to prevent seizures from recurring”