What is the management of severe preeclampsia?

Management of Severe Preeclampsia

Severe preeclampsia requires immediate dual therapy with intravenous magnesium sulfate for seizure prophylaxis and aggressive blood pressure control with IV labetalol, followed by expedited delivery after maternal stabilization. 1, 2, 3

Immediate Stabilization (First 30 Minutes)

Magnesium Sulfate Administration

• Administer magnesium sulfate immediately for all patients with severe preeclampsia (BP ≥160/110 mmHg) or those with neurological symptoms. 1, 2, 3
• Loading dose: 4-5g IV over 5 minutes, followed by maintenance infusion of 1-2g/hour continuous IV 3, 4
• Alternative regimen: 4-5g IV plus simultaneous IM doses of up to 10g (5g in each buttock), then 4-5g IM into alternate buttocks every 4 hours 4
• Target serum magnesium level: 6 mg/100 mL for optimal seizure control 4
• Critical warning: Do not continue magnesium sulfate beyond 5-7 days as it causes fetal abnormalities 4

Blood Pressure Control

• Initiate IV antihypertensive therapy immediately when BP ≥160/110 mmHg persists for more than 15 minutes 1, 3
• First-line agent: IV labetalol 1, 2, 3
  • Dosing: 20mg IV bolus, then 40mg after 10 minutes, followed by 80mg every 10 minutes to maximum 220mg 2
  • Maximum rate: Do not exceed 150 mg/minute IV injection except in severe eclampsia with seizures 4
• Alternative agents: IV hydralazine or IV nicardipine 1
• Target BP: Systolic 110-140 mmHg and diastolic 85 mmHg (or at minimum <160/105 mmHg) 1, 2, 3
• The goal is to decrease mean BP by 15-25% to prevent maternal cerebral hemorrhage while maintaining uteroplacental perfusion 1, 3

Medications to Avoid

• Short-acting oral nifedipine should be avoided, especially when combined with magnesium sulfate, due to risk of uncontrolled hypotension and fetal compromise 1
• ACE inhibitors and ARBs are absolutely contraindicated in pregnancy due to severe fetotoxicity including renal failure, oligohydramnios, growth restriction, and fetal death 2, 3
• Diuretics are contraindicated as they further reduce plasma volume 3
• Sodium nitroprusside should only be used as last resort for extreme emergencies due to risk of fetal cyanide poisoning 1

Critical Monitoring Requirements

Maternal Monitoring

• Continuous BP monitoring during antihypertensive administration 2
• Monitor deep tendon reflexes before each magnesium dose to detect toxicity 2, 3
• Respiratory rate monitoring (magnesium toxicity causes respiratory depression) 2, 3
• Hourly urine output via Foley catheter with target ≥100 mL/4 hours (or >35 mL/hour) 1, 3
• Oxygen saturation on room air (maternal early warning if <95%) 1
• Assess for maternal agitation, confusion, or unresponsiveness 1
• Monitor for non-remitting headache and shortness of breath 1

Laboratory Monitoring

• Obtain at least twice weekly (or more frequently with clinical deterioration): hemoglobin, platelet count, liver transaminases, creatinine, and uric acid 1, 2, 3
• Complete blood count and comprehensive metabolic panel to assess for HELLP syndrome 3
• Peripheral blood smear if hemolysis suspected 3
• Spot urine protein/creatinine ratio (≥30 mg/mmol confirms significant proteinuria) 3

Fetal Monitoring

• Continuous fetal heart rate monitoring 3
• Ultrasound assessment at diagnosis: fetal biometry, amniotic fluid, and umbilical artery Doppler 1
• Repeat ultrasound every 2 weeks if initial assessment normal, more frequently if fetal growth restriction present 1

Delivery Timing (Gestational Age-Based Algorithm)

≥37 Weeks Gestation

• Deliver immediately after maternal stabilization 1, 2, 3
• Induction of labor is associated with improved maternal outcome 1

34-37 Weeks Gestation

• Expectant conservative management is appropriate if maternal and fetal status stable 1
• Deliver if any maternal or fetal deterioration occurs 1

<34 Weeks Gestation

• Conservative expectant management at a center with Maternal-Fetal Medicine expertise 1
• Administer antenatal corticosteroids 5
• Average pregnancy prolongation: 7-10 days (range 4-28 days) 6, 7
• Expectant management at 24-32 weeks improves neonatal outcome in select cases 6

Absolute Indications for Immediate Delivery (Regardless of Gestational Age)

• Inability to control BP despite ≥3 classes of antihypertensives in appropriate doses 1
• Progressive thrombocytopenia or progressively abnormal liver/renal function tests 1
• Pulmonary edema 1
• Severe intractable headache, repeated visual scotomata, or convulsions 1
• Placental abruption 3
• Non-reassuring fetal status 1
• Maternal pulse oximetry deterioration 1

Special Considerations for Pulmonary Edema

• Drug of choice: IV nitroglycerin (glycerol trinitrate) starting at 5 mcg/min, gradually increased every 3-5 minutes to maximum 100 mcg/min 1
• Plasma volume expansion is not recommended routinely 1, 5

HELLP Syndrome Recognition

• Characterized by hemolysis, elevated liver enzymes (AST/ALT), and low platelets (<100,000) 3
• Epigastric or right upper quadrant pain is hallmark symptom suggesting hepatic capsule distension 3
• Maternal mortality rate: 3.4% 3
• Monitor glucose intraoperatively as severe hypoglycemia can occur 3

Transfer Considerations

• All patients with severe preeclampsia should be considered for medicalized transport to a specialized obstetric center 3
• Initiate magnesium sulfate and BP control prior to transport 3
• Coordinate with obstetric and anesthetic-intensivist teams at receiving facility before transfer 3

Common Pitfalls to Avoid

• Do not attempt to diagnose "mild versus severe" preeclampsia clinically—all cases may become emergencies rapidly 1
• Do not use serum uric acid or level of proteinuria as indication for delivery 1
• Do not combine magnesium sulfate with calcium channel blockers due to severe hypotension risk 2
• Do not reduce antihypertensives if diastolic BP falls <80 mmHg 1
• For gestational age <24 weeks, expectant management is associated with high maternal morbidity with limited perinatal benefit—counsel regarding pregnancy termination 1, 6