What is the management plan for pre-eclampsia with severe features?

Management of Pre-eclampsia with Severe Features

Immediate administration of magnesium sulfate for seizure prophylaxis and aggressive blood pressure control with IV antihypertensives are the cornerstones of managing severe pre-eclampsia, followed by expedited delivery after maternal stabilization. 1, 2

Immediate Pharmacologic Management

Magnesium Sulfate Administration (First Priority)

Magnesium sulfate must be administered immediately to all patients with severe pre-eclampsia who have at least one clinical sign of seriousness to prevent progression to eclampsia. 1, 3

Dosing regimen: 4

• Loading dose: 4-5 g IV over 5 minutes (diluted in 250 mL of 5% dextrose or 0.9% saline)
• Maintenance: 1-2 g/hour continuous IV infusion
• Alternative IM regimen: 4 g IV loading dose followed by 10 g IM (5 g in each buttock), then 5 g IM every 4 hours in alternating buttocks

Target therapeutic level: 1.8-3.0 mmol/L (6 mg/100 mL) for seizure control 4, 5

Critical warning: Do not continue magnesium sulfate beyond 5-7 days as it can cause fetal abnormalities 4

Blood Pressure Control (Concurrent Priority)

Initiate IV antihypertensive therapy immediately when systolic BP ≥160 mmHg and/or diastolic BP ≥110 mmHg persisting for more than 15 minutes. 1, 2

Target blood pressure: 2

• Systolic: 110-140 mmHg
• Diastolic: 85 mmHg

First-line IV antihypertensive options: 2, 6, 7

• Labetalol (preferred in most settings)
• Hydralazine (traditional first choice in Australia)
• Nicardipine

Critical contraindication: Never combine magnesium sulfate with IV or sublingual nifedipine—this causes severe myocardial depression 3

Clinical Monitoring Protocol

Maternal Monitoring (No Routine Magnesium Levels Needed)

Clinical examination is sufficient to detect magnesium toxicity—do not routinely draw magnesium levels. 3, 2

Monitor every 15-30 minutes: 3, 2, 5

• Patellar reflexes: Loss indicates impending toxicity (occurs at 3.5-5 mmol/L)
• Respiratory rate: Must remain >12 breaths/minute (paralysis occurs at 5-6.5 mmol/L)
• Urine output: Must maintain ≥30 mL/hour (oliguria increases toxicity risk)
• Oxygen saturation: Keep >90%
• Blood pressure: Continuous monitoring

Check magnesium levels ONLY if: 3

• Renal impairment (elevated creatinine)
• Loss of patellar reflexes
• Respiratory rate <12/minute
• Oliguria develops

Laboratory Assessment

Initial workup: 2

• Complete blood count (assess for HELLP syndrome)
• Comprehensive metabolic panel (creatinine, liver enzymes)
• Peripheral blood smear (evaluate for hemolysis)
• Spot urine protein/creatinine ratio (≥30 mg/mmol confirms significant proteinuria)

Repeat labs at least twice weekly or more frequently if clinical deterioration occurs 2

Transfer and Coordination

Medicalised transport to a specialized obstetric center should be systematically considered for all patients with severe pre-eclampsia. 1

Before transfer: 1

• Coordinate with obstetric and anesthetic-intensivist teams at receiving facility via phone
• Discuss antihypertensive treatment initiation and modalities
• Involve emergency medical assistance service regulating doctor
• Initiate magnesium sulfate and blood pressure control prior to transport

Delivery Planning

Delivery is the definitive treatment and should be planned after maternal stabilization. 2, 6

Indications for immediate delivery: 2

• Gestational age ≥34 weeks
• Severe persistent headache despite treatment
• Deteriorating renal function
• HELLP syndrome
• Eclampsia
• Non-reassuring fetal status

Preferred route: Vaginal delivery unless cesarean indicated for obstetric reasons 2

Medications to Absolutely Avoid

2

• ACE inhibitors, ARBs, direct renin inhibitors: Severe fetotoxicity
• Diuretics: Further reduce plasma volume (already contracted in pre-eclampsia)
• IV/sublingual nifedipine with magnesium sulfate: Severe myocardial depression

Common Pitfalls

Maximum dosing limits: 4

• Do not exceed 30-40 g magnesium sulfate per 24 hours in normal renal function
• In severe renal insufficiency, maximum is 20 g per 48 hours with frequent serum monitoring

Toxicity progression: 5

• 3.5-5 mmol/L: Loss of patellar reflexes
• 5-6.5 mmol/L: Respiratory paralysis

• 7.5 mmol/L: Altered cardiac conduction

• 12.5 mmol/L: Cardiac arrest

Antidote: Keep calcium gluconate (1 g IV over 3 minutes) immediately available to reverse magnesium toxicity 5