What is the next step for a 36-week pregnant woman presenting with symptoms of preeclampsia, including headache, restlessness, and hypertension (elevated blood pressure), who develops generalized seizures?

Immediate Management of Eclampsia at 36 Weeks Gestation

The next step is immediate IV magnesium sulfate administration (Option C) for seizure control and prophylaxis, followed by urgent blood pressure control with IV antihypertensives after maternal stabilization. 1, 2

Rationale for Magnesium Sulfate as First-Line Treatment

This patient has progressed from severe preeclampsia (headache, restlessness, BP 160/90) to eclampsia with generalized seizures. Magnesium sulfate is the definitive first-line anticonvulsant for eclamptic seizures and must be administered immediately. 1, 2

• Loading dose: 4-5 g IV over 5 minutes (diluted in 250 mL of 5% dextrose or 0.9% normal saline) 1, 3
• Maintenance dose: 1-2 g/hour continuous IV infusion 1, 3
• Duration: Continue for at least 24 hours postpartum, as eclampsia can occur in the postpartum period 2

Magnesium sulfate prevents or controls convulsions by blocking neuromuscular transmission and decreasing acetylcholine release at the motor end-plate. 4 The onset of anticonvulsant action is immediate with IV administration and lasts approximately 30 minutes. 4 Effective anticonvulsant serum levels range from 2.5 to 7.5 mEq/L. 4

Why Not Phenytoin (Option B)?

Phenytoin is not the appropriate first-line agent for eclamptic seizures. 1, 2 While older literature suggested phenytoin might be used, current evidence-based guidelines uniformly recommend magnesium sulfate as the definitive anticonvulsant for eclampsia. 1, 2, 5 Magnesium sulfate has been proven superior in preventing recurrent seizures and reducing maternal mortality compared to phenytoin or other traditional anticonvulsants. 5

Why Not Observation (Option A)?

Observation alone is dangerous and inappropriate for a patient actively seizing with eclampsia. 1, 2 This is a hypertensive emergency requiring immediate intervention to prevent:

• Maternal cerebral hemorrhage 1, 2
• Recurrent seizures (recurrence rate 2% without magnesium vs 0.6% with magnesium) 2
• Maternal death (HELLP syndrome carries 3.4% maternal mortality) 1, 3
• Placental abruption 3
• Fetal compromise and death 5, 6

Concurrent Urgent Blood Pressure Management

After initiating magnesium sulfate, severe hypertension (≥160/110 mmHg) requires immediate treatment within 15 minutes to prevent maternal cerebral hemorrhage. 1, 2

First-line IV antihypertensive options:

• IV labetalol: 20 mg IV bolus, then 40 mg after 10 minutes, then 80 mg every 10 minutes (maximum cumulative dose 220 mg) 1, 3
• IV hydralazine: 5-10 mg IV every 20 minutes as needed 3
• Oral nifedipine: Preferred first-line agent for urgent BP control 2

Target blood pressure: Systolic 110-140 mmHg and diastolic 85 mmHg (or at minimum <160/105 mmHg) 1, 3, 2

Critical Monitoring Requirements During Magnesium Therapy

• Deep tendon reflexes: Assess before each dose to monitor for magnesium toxicity (reflexes disappear at plasma levels approaching 10 mEq/L) 1, 4
• Respiratory rate: Monitor for respiratory depression (respiratory paralysis may occur at 10 mEq/L) 1, 4
• Urine output: Hourly monitoring via Foley catheter with target ≥100 mL/4 hours (or >35 mL/hour), as magnesium is excreted solely by the kidneys 1, 2, 4
• Oxygen saturation: Maintain >95% on room air 1
• Continuous blood pressure monitoring: Every 4 hours minimum 2

Antidote for magnesium toxicity: IV calcium gluconate should be immediately available. 1

Comprehensive Laboratory Assessment

Obtain immediately:

• Complete blood count: Assess for thrombocytopenia (<100,000/μL) and hemolysis 1, 3, 2
• Comprehensive metabolic panel: AST/ALT (elevated ≥2x upper limit indicates severe disease), creatinine (>1.1 mg/dL indicates renal dysfunction), uric acid 1, 3, 2
• Spot urine protein/creatinine ratio: ≥30 mg/mmol confirms significant proteinuria 3

Delivery Planning at 36 Weeks

Delivery is the definitive treatment for eclampsia and should occur after maternal stabilization. 2

At 36 weeks gestation, this patient meets criteria for immediate delivery after maternal stabilization because:

• Eclamptic seizures are an absolute indication for immediate delivery regardless of gestational age 1, 3
• At ≥34 weeks with severe features, deliver after maternal stabilization 1, 3

Induction of labor is associated with improved maternal outcomes compared to expectant management. 7

Critical Pitfalls to Avoid

• Do not delay magnesium sulfate administration while waiting for laboratory results or imaging 1, 2
• Do not use diuretics routinely—they further reduce plasma volume which is already contracted in preeclampsia 3
• Limit total fluid intake to 60-80 mL/hour to avoid pulmonary edema risk 7, 2
• Do not underestimate disease severity—25% of eclamptic women were normotensive or had only mild-to-moderate hypertension immediately before seizure 8
• Avoid NSAIDs for postpartum analgesia, especially with renal dysfunction, as they can worsen hypertension and renal function 3, 2

Special Consideration: HELLP Syndrome

Monitor closely for HELLP syndrome (hemolysis, elevated liver enzymes, low platelets), which carries 3.4% maternal mortality. 1, 3 Epigastric or right upper quadrant pain is the hallmark symptom and indicates hepatic capsule distension. 1, 3 Severe hypoglycemia can occur and should be monitored intraoperatively. 1