Primary Treatment for Eclampsia
Immediate intravenous magnesium sulfate is the definitive first-line treatment for eclampsia, combined with urgent blood pressure control using IV labetalol or nicardipine, followed by delivery after maternal stabilization. 1, 2
Immediate Seizure Management
Magnesium sulfate is the only anticonvulsant that should be used for eclampsia—it is superior to diazepam, phenytoin, and all other anticonvulsants for both treating active seizures and preventing recurrence. 2, 3, 4
Magnesium Sulfate Dosing
- IV route: 4-5g IV over 5 minutes (diluted in 250mL of 5% dextrose or 0.9% saline)
- Combined IV/IM route: 4g IV plus 10g IM (5g in each buttock) for total loading dose of 14g
- IM-only route (if IV unavailable): 10g IM total (5g in each buttock) 6
- 1-2g/hour continuous IV infusion, OR
- 4-5g IM into alternate buttocks every 4 hours (Pritchard regimen)
Duration: Continue for 24 hours after delivery or 24 hours after the last seizure, whichever is later. 2, 6 Note that 25-30% of eclamptic seizures occur postpartum, requiring continued vigilance. 2, 6
Critical Monitoring for Magnesium Toxicity
Before each dose, verify these three safety parameters: 5
- Patellar reflexes present (reflexes disappear at 10 mEq/L, indicating impending toxicity)
- Respiratory rate ≥16 breaths/minute (respiratory paralysis occurs at 10 mEq/L)
- Urine output ≥100mL over preceding 4 hours
Therapeutic serum magnesium level: 3-6 mg/100mL (2.5-5 mEq/L) 5
Have calcium gluconate immediately available as the antidote for magnesium toxicity. 5, 6
Blood Pressure Management
Target blood pressure: <160/105 mmHg, ideally systolic 110-140 mmHg and diastolic 85 mmHg. 1, 2
First-Line IV Antihypertensives
- 20mg IV bolus initially
- Then 40mg after 10 minutes
- Then 80mg every 10 minutes
- Maximum total dose: 220mg
Nicardipine (alternative first-line): 1, 2
- Start at 5mg/hour IV
- Increase by 2.5mg/hour every 5-15 minutes
- Maximum: 15mg/hour
Hydralazine (second-line): 1, 6
- Use when labetalol/nicardipine unavailable
- Administer per institutional protocol
Critical caveat: There is risk of severe hypotension when combining magnesium sulfate with calcium channel blockers like nifedipine—use with extreme caution. 1, 6
Fluid Management
Restrict total fluid intake to 60-80mL/hour to prevent pulmonary edema, as eclamptic women have capillary leak and reduced plasma volume. 2, 6 This replaces insensible losses (30mL/hour) plus anticipated urinary output (0.5-1mL/kg/hour). 6
Diuretics are absolutely contraindicated because plasma volume is already reduced in eclampsia. 1, 6
Delivery Planning
Delivery is the only definitive cure for eclampsia. Plan for delivery after maternal stabilization with magnesium sulfate and blood pressure control. 2, 6, 7
Vaginal delivery is preferred unless cesarean section is indicated for obstetric reasons. 2, 6
Immediate delivery indications regardless of gestational age: 6
- Inability to control blood pressure despite 3 antihypertensive classes
- Progressive thrombocytopenia or HELLP syndrome
- Progressively abnormal renal or liver function tests
- Pulmonary edema
- Recurrent seizures despite magnesium
- Non-reassuring fetal status
- Placental abruption
Antenatal corticosteroids: Administer if gestational age ≤34 weeks to accelerate fetal lung maturation; may be given up to 38 weeks for elective cesarean section. 1, 6 Multiple courses are not recommended. 1, 6
Common Pitfalls to Avoid
Never use sodium nitroprusside except as absolute last resort—it causes fetal cyanide toxicity. 2, 6
Never use ACE inhibitors or ARBs—they cause fetal renal dysgenesis, oligohydramnios, growth restriction, and fetal death. 8
Avoid NSAIDs postpartum in women with eclampsia, especially with acute kidney injury—use alternative analgesia. 6
Do not exceed 30-40g magnesium sulfate in 24 hours. 5 In severe renal insufficiency, maximum is 20g/48 hours with frequent serum magnesium monitoring. 5
Never continue magnesium sulfate beyond 5-7 days in pregnancy—prolonged use causes fetal hypocalcemia, skeletal demineralization, osteopenia, and neonatal fractures. 5
Postpartum Management
Continue magnesium sulfate for 24 hours postpartum or 24 hours after last seizure. 2, 6
Monitor blood pressure every 4-6 hours for at least 3 days postpartum. 2, 6
Continue antihypertensive therapy during labor and postpartum, tapering slowly only after days 3-6 postpartum unless BP <110/70 mmHg. 6
Blood pressure and urine should be checked at 6 weeks postpartum, with assessment for secondary causes of hypertension in women under 40 with persistent hypertension. 6