What are the management strategies for preeclampsia in obstetrics and gynaecology?

Management of Preeclampsia for Postgraduate Examination

Immediate Recognition and Severity Assessment

For any patient presenting with suspected preeclampsia, immediately assess blood pressure and initiate urgent antihypertensive therapy if systolic BP ≥160 mmHg or diastolic BP ≥110 mmHg persisting for more than 15 minutes, while simultaneously administering magnesium sulfate for seizure prophylaxis if severe features are present. 1, 2

Diagnostic Criteria

• Preeclampsia is diagnosed by new-onset hypertension (≥140/90 mmHg) after 20 weeks of gestation with either proteinuria (≥+ on dipstick or protein/creatinine ratio ≥30 mg/mmol) or evidence of end-organ damage 1, 3
• Severe preeclampsia is defined by BP ≥160/110 mmHg with neurological symptoms (severe headache, visual disturbances), renal dysfunction (elevated creatinine, oliguria), thrombocytopenia (<100,000/μL), elevated liver enzymes (>2x normal), or pulmonary edema 2, 3
• HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets) represents a severe variant with 3.4% maternal mortality and requires immediate recognition 2

Critical Initial Actions Within First 15 Minutes

• Measure BP on repeat to confirm elevation; severe hypertension requires treatment within 15 minutes to prevent maternal stroke 1, 2
• Perform dipstick urinalysis immediately; ≥+ proteinuria with hypertension warrants same-day hospital assessment 1
• Assess for symptoms of severity: severe headache, visual scotomata, epigastric/right upper quadrant pain (indicating hepatic capsule distension), shortness of breath 1, 2
• Evaluate deep tendon reflexes and check for clonus (hyperreflexia indicates increased seizure risk) 2, 3

Blood Pressure Management Algorithm

For Severe Hypertension (≥160/110 mmHg)

First-line treatment: IV labetalol 20 mg bolus, then 40 mg after 10 minutes if BP remains elevated, followed by 80 mg every 10 minutes to maximum cumulative dose of 220 mg. 2

• Alternative first-line: Oral nifedipine 10 mg, repeat every 20 minutes to maximum 30 mg 3, 4
• Second-line: IV nicardipine or IV hydralazine (though hydralazine has more perinatal adverse effects) 2, 4
• Target BP: Systolic 110-140 mmHg and diastolic 85 mmHg (absolute minimum <160/105 mmHg) 2, 3
• Goal is to decrease mean arterial pressure by 15-25% to prevent maternal cerebral hemorrhage while maintaining uteroplacental perfusion 2

For Non-Severe Hypertension (140-159/90-109 mmHg)

• Initiate oral antihypertensives: methyldopa, labetalol, or long-acting nifedipine 3
• Target diastolic BP of 85 mmHg and systolic 110-140 mmHg 3
• Monitor BP every 4 hours while awake 3

Absolute Contraindications in Pregnancy

• ACE inhibitors, ARBs, and direct renin inhibitors are absolutely contraindicated due to severe fetotoxicity causing renal dysgenesis 2, 3, 4
• Avoid sublingual or short-acting oral nifedipine, especially when combined with magnesium sulfate, due to risk of uncontrolled hypotension and fetal compromise 2, 3
• Sodium nitroprusside only as last resort for extreme emergencies due to risk of fetal cyanide poisoning 2
• Diuretics are contraindicated as they further reduce plasma volume already compromised in preeclampsia 2, 3

Magnesium Sulfate Administration Protocol

Administer magnesium sulfate immediately to all patients with severe preeclampsia or those with at least one clinical sign of seriousness (severe headache, visual disturbances, hyperreflexia, epigastric pain) to prevent eclamptic seizures. 1, 2, 3

Dosing Regimen

• Loading dose: 4-5 g IV over 5 minutes 2
• Maintenance: 1-2 g/hour continuous IV infusion 2
• Continue for 24 hours postpartum 3
• The 50% solution must be diluted to 20% or less prior to IV infusion 5

Monitoring Requirements During Magnesium Therapy

• Check patellar reflex (knee jerk) before each dose; if absent, hold magnesium until reflexes return 5
• Monitor respiratory rate continuously; must be ≥16 breaths/minute (respiratory depression indicates toxicity) 5
• Maintain urine output ≥100 mL per 4 hours (or >35 mL/hour) via Foley catheter 2, 5
• Therapeutic serum magnesium level: 3-6 mg/100 mL (2.5-5 mEq/L) 5
• Deep tendon reflexes diminish when levels exceed 4 mEq/L; reflexes absent at 10 mEq/L with risk of respiratory paralysis 5
• Have IV calcium gluconate immediately available at bedside to counteract magnesium toxicity 5

Magnesium Toxicity Signs

• Loss of patellar reflexes (earliest sign) 5
• Respiratory rate <12 breaths/minute 5
• Oxygen saturation <95% 2
• Flushing and sweating (administer with caution if occurs) 5

Critical FDA Warning

• Continuous administration beyond 5-7 days can cause fetal hypocalcemia, skeletal demineralization, osteopenia, and neonatal fractures 5
• Use shortest duration necessary; inform patients that efficacy for preterm labor is not established 5

Comprehensive Laboratory and Monitoring Protocol

Initial Laboratory Assessment

• Complete blood count with hemoglobin and platelet count 2, 3
• Comprehensive metabolic panel including liver transaminases (AST, ALT), creatinine, and uric acid 2, 3
• Peripheral blood smear if HELLP syndrome suspected (look for schistocytes indicating hemolysis) 2
• Spot urine protein/creatinine ratio to quantify proteinuria (≥30 mg/mmol confirms significant proteinuria) 2, 3
• 24-hour urine collection is most reliable method for quantifying protein excretion 1

Ongoing Monitoring Frequency

• Repeat laboratory tests at least twice weekly, or more frequently if clinical deterioration occurs 2, 3
• Blood pressure measurements every 4 hours while awake (more frequently if severe hypertension) 3
• Continuous maternal monitoring in severe cases: BP, oxygen saturation, respiratory rate, urine output 2
• Assess for maternal agitation, confusion, unresponsiveness, non-remitting headache 2

Fetal Surveillance Protocol

• Initial ultrasound at diagnosis: fetal biometry, amniotic fluid volume, umbilical artery Doppler 2, 3
• Repeat ultrasound every 2 weeks if initial assessment normal; more frequently if fetal growth restriction present 2
• Continuous fetal heart rate monitoring in severe cases 3, 4
• Non-stress test and biophysical profile for ongoing assessment 6

Fluid Management Strategy

Strictly limit total fluid intake to 60-80 mL/hour to prevent pulmonary edema, which is a leading cause of maternal death in preeclampsia. 2, 3

• Aim for euvolemia; avoid "running dry" as this increases acute kidney injury risk 3
• Plasma volume expansion is not recommended routinely 2
• Monitor hourly urine output via Foley catheter with target ≥100 mL/4 hours 2
• If pulmonary edema develops: IV nitroglycerin starting at 5 mcg/min, gradually increased every 3-5 minutes to maximum 100 mcg/min 2

Timing of Delivery Algorithm

Delivery is the definitive treatment for preeclampsia; timing depends on gestational age, severity of maternal condition, and fetal status. 3

Immediate Delivery Indications (Regardless of Gestational Age)

• Inability to control BP despite ≥3 classes of antihypertensives in appropriate doses 2, 3
• Progressive thrombocytopenia or progressively abnormal liver/renal function tests 2, 3
• Pulmonary edema 2, 3
• Severe intractable headache, repeated visual scotomata, or eclamptic seizures 2, 3
• Non-reassuring fetal status 2, 3
• Placental abruption 2, 3
• Maternal pulse oximetry deterioration 2

Gestational Age-Specific Management

≥37 weeks: Deliver immediately after maternal stabilization with magnesium sulfate and BP control 2, 3

34-37 weeks:

• Expectant conservative management appropriate if maternal and fetal status stable 2
• Deliver if any maternal or fetal deterioration occurs 2
• Induction of labor is associated with improved maternal outcome 2

<34 weeks:

• Administer corticosteroids for 48 hours to accelerate fetal lung maturation 3
• Conservative expectant management at a center with Maternal-Fetal Medicine expertise 2
• Average interval from diagnosis to delivery is 14 days, but some require delivery within 72 hours 2

<24 weeks:

• Expectant management associated with high maternal morbidity with limited perinatal benefit 2
• Counsel regarding pregnancy termination 2
• If preeclampsia occurs before 20 weeks, consider alternative diagnoses such as hydatidiform mole 4

Transfer and Coordination Protocols

Medicalised transport to a specialized obstetric center should be systematically considered for all patients with severe preeclampsia, coordinated with the emergency medical assistance service regulating doctor. 1, 2

Pre-Transfer Actions

• Initiate antihypertensive treatment and magnesium sulfate prior to transport 1
• Phone consultation with obstetric and anesthetic-intensivist teams at receiving facility to discuss treatment modalities 1
• Ensure receiving facility has maternal intensive care capabilities and neonatal intensive care unit for extremely premature infants 4
• Consider presence of neonatal back-up team if delivery anticipated 1

Mode of Delivery Considerations

• Vaginal delivery is preferred unless cesarean indicated for obstetric reasons 2
• Regional anesthesia (epidural/spinal) is preferred over general anesthesia when possible 7
• Do not administer NSAIDs for analgesia if delivery occurs, as they worsen renal function in preeclampsia 4

Postpartum Management

Continue close monitoring for at least 3 days postpartum as eclampsia can still develop; 34% of eclamptic women in UK had maximum diastolic BP ≤100 mmHg, demonstrating that severe hypertension is not always present. 1, 3

Postpartum Monitoring Protocol

• Monitor BP at least every 4 hours while awake 3
• Continue magnesium sulfate for 24 hours postpartum 3
• Continue antihypertensives and taper slowly after days 3-6 postpartum 3
• Watch for signs of pulmonary edema (most common in first 72 hours postpartum) 2

Long-Term Counseling

• Women with preeclampsia have increased lifetime cardiovascular risk and should receive appropriate counseling 3
• Regular exercise during future pregnancies may help reduce likelihood of hypertension 3

Prevention Strategies for High-Risk Women

Low-dose aspirin (75-162 mg/day) started before 16 weeks' gestation (definitely before 20 weeks) for women with strong clinical risk factors reduces preeclampsia incidence. 3, 7, 6

High-Risk Factors Warranting Aspirin Prophylaxis

• Previous preeclampsia, especially early-onset 3, 7
• Chronic hypertension 7, 6
• Pregestational diabetes 7, 6
• Renal disease 7, 6
• Autoimmune disease (systemic lupus erythematosus, antiphospholipid syndrome) 7, 6
• Multi-fetal pregnancy 6
• Advanced maternal age 6
• Obesity 6

Additional Prevention

• Supplemental calcium (1.2-2.5 g/day) if dietary intake likely low (<600 mg/day) 3, 7
• Do not use low molecular weight heparin for prevention, even with prior early-onset preeclampsia 4

Common Pitfalls to Avoid

• Do not attempt to diagnose "mild versus severe" preeclampsia clinically—all cases may become emergencies rapidly 2
• Do not use serum uric acid level or degree of proteinuria as indications for delivery 2, 4
• Do not reduce antihypertensives if diastolic BP falls <80 mmHg 2
• Do not use blood pressure level alone to determine disease severity; serious organ dysfunction can develop at relatively mild BP elevations 4
• Oedema is not predictive and weight change does not reliably precede other signs 1
• A + result on dipstick testing alone is prone to false positives; accuracy not increased by repeating test on new sample 1
• Do not combine IV magnesium with calcium channel blockers due to myocardial depression risk 3

Special Clinical Scenarios

New Hypertension Without Proteinuria

• Diastolic 90-99 mmHg: Refer for hospital assessment within 48 hours 1
• Diastolic 90-99 mmHg with any symptoms (headache, visual disturbances, epigastric pain): Same day hospital assessment 1
• Systolic ≥160 mmHg or diastolic ≥100 mmHg: Same day hospital assessment 1
• Women with new hypertension before 32 weeks have 50% chance of developing preeclampsia 1

New Proteinuria Without Hypertension

• • on dipstick: Repeat preeclampsia assessment in community within one week 1
• ≥++ on dipstick: Hospital assessment within 48 hours 1
• ≥+ with any symptoms: Same day hospital assessment 1

Maternal Symptoms Without Hypertension or Proteinuria

• Headache or visual disturbances: Follow local protocols, consider reducing interval before next assessment 1
• Epigastric pain: Same day hospital assessment (may indicate HELLP syndrome developing) 1
• Reduced fetal movements or small for gestational age: Follow local protocols for investigation 1