• fosphenytoin 20 mg PE/kg IV at 150 mg PE/min

If persistent:

• levetiracetam 60 mg/kg IV, maximum 4,500 mg
• Consider intubation with propofol, consider consulting with neurology and plan for ICU admission

Resolution of Seizure⁶

Once seizure has been aborted, consider the following steps in ongoing resuscitation

1. Assess BP: if systolic blood pressure >160 or diastolic blood pressure >110, initiate the Acute Hypertension Algorithm
2. OB evaluation ASAP
3. If seizure responds to magnesium and urgent transport to an obstetric unit for further evaluation is unavailable:
   1. Continue magnesium sulfate infusion 1-2 g/hr.
   2. Monitor magnesium levels every four hours (therapeutic range 4.9-8.5 mg/dL).
   3. Observe for magnesium toxicity.
4. Maintain infusion for at least 24-48 hours after last seizure or delivery, whichever occurred latest.
5. Obtain head computed tomography scan to rule out intracranial hemorrhage versus ischemia.
6. Perform a thorough neurological exam.
7. Preparation for delivery as applicable based on emergency department resources (i.e., admission to Labor and Delivery, transfer to facility with Labor and Delivery).

Magnesium Toxicity⁷

• If serum magnesium >9.6 mg/dL, the infusion should be stopped and can be restarted once the level decreases to <8.4 mg/dL.
• If a patient is demonstrating signs of respiratory depression secondary to magnesium toxicity, calcium gluconate or calcium chloride should be used as calcium directly antagonizes neuromuscular and cardiovascular effects of magnesium.
  • 10 percent calcium gluconate: 2-3 grams IV over three minutes
  • Ensure IV hydration to maintain magnesium excretion.
• Effects of magnesium toxicity compound as the serum magnesium levels (mg/dL) increase. For reference:
  • 4.9-8.5: therapeutic range
  • 8.5-12: loss of deep tendon reflexes
  • 12-15: respiratory depression
  • >18: effects of cardiac conduction
  • >30: cardiac arrest

Conclusion

Eclampsia is a severe complication of pregnancy that poses significant risks to both the mother and the fetus. It is associated with maternal and fetal morbidity and mortality if not managed properly. Early identification of preeclampsia and timely medical intervention, such as the administration of magnesium sulfate to prevent seizures and the delivery of the baby, are crucial in mitigating the dangers of eclampsia. With appropriate care and management, many patients can go on to have healthy pregnancies, but awareness and vigilance remain essential for safeguarding the health of both parent and child.

Dr. Wiltz is a PGY-3 in emergency medicine and chief resident at Case Western Reserve University/University Hospitals in Cleveland, Ohio. She is also president-elect of the Emergency Medicine Residents’ Association.

References

1. Gestational Hypertension and Preeclampsia: ACOG Practice Bulletin, Number 222. Obstet Gynecol. 2020;135(6):e237-e260.
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4. ACOG. Acute Hypertension in Pregnancy and Postpartum Algorithm. https://www.acog.org/-/media/secure/programs/acog_urgent-care-acute-hypertension-in-pregnancy-and-postpartum-algorithm.pdf. Accessed July 9, 2025.
5. Sibai BM. Magnesium sulfate prophylaxis in preeclampsia: Lessons learned from recent trials. Am J Obstet Gynecol. 2004;190(6):1520-1526.
6. Schoen JC, Campbell RL, Sadosty AT. Headache in pregnancy: an approach to emergency department evaluation and management. West J Emerg Med. 2015;16(2):291-301.
7. Kerrigan K, Smith L. Preeclampsia/Eclampsia. In: Swadron S, Nordt S, Mattu A, and Johnson W, eds. CorePendium. 5th ed. Burbank, CA: CorePendium, LLC. https://www.emrap.org/corependium/chapter/rec09jiLmoJ1dIM0l/PreeclampsiaEclampsia#h.y2w33fax0jwc. Updated February 7, 2025. Accessed April 4, 2025.

[This article was corrected on October 16, 2025, to state the appropriate laboratory levels for magnesium toxicity.]