What are the prevention, diagnosis, and management strategies for a pregnant woman at risk of eclampsia, particularly those with a history of hypertension or other risk factors?

Eclampsia Prevention, Diagnosis, and Management

Prevention in High-Risk Women

All women with strong clinical risk factors for preeclampsia (prior preeclampsia, chronic hypertension, pregestational diabetes, BMI >30 kg/m², antiphospholipid syndrome, or assisted reproduction) should receive low-dose aspirin 75-162 mg daily, ideally before 16 weeks but definitely before 20 weeks of gestation. 1, 2

Risk Factor Identification

• Strong clinical risk factors requiring aspirin prophylaxis include: prior preeclampsia, chronic hypertension, pregestational diabetes mellitus, maternal BMI >30 kg/m², antiphospholipid syndrome, and receipt of assisted reproduction 1
• Additional risk factors include nulliparity, multifetal gestation, African American race, advanced maternal age, renal disease, and autoimmune diseases 1

Additional Preventive Measures

• Supplemental calcium 1.2-2.5 g/day should be given if dietary intake is likely low (<600 mg/day) 1, 2
• Regular exercise during pregnancy reduces the likelihood of developing hypertension 1
• Low molecular weight heparin is NOT indicated for preeclampsia prevention, even with prior early-onset preeclampsia 1

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Screening and Diagnosis

Blood pressure should be measured at every prenatal visit throughout pregnancy using proper technique: patient seated with legs uncrossed, back supported, arm at heart level, after 5 minutes of rest, using a large cuff if upper arm circumference ≥33 cm. 1

Diagnostic Criteria

• Preeclampsia is diagnosed by new-onset hypertension (≥140/90 mmHg) after 20 weeks of gestation with proteinuria or evidence of end-organ damage 2
• Proteinuria is optimally assessed by automated dipstick screening, then quantified with urine protein/creatinine ratio ≥30 mg/mmol (0.3 mg/mg) 1
• Severe features include: severe hypertension (≥160/110 mmHg), thrombocytopenia, elevated liver enzymes, renal insufficiency, pulmonary edema, or neurological symptoms (severe headache, visual disturbances) 2, 3

Initial Assessment

• All women with preeclampsia should be hospitalized initially to confirm diagnosis, assess severity, and monitor progression 1, 2
• Obtain baseline laboratory tests at least twice weekly: complete blood count with hemoglobin and platelets, liver enzymes (AST/ALT), creatinine, and uric acid 1, 2
• Initial fetal assessment should confirm well-being using ultrasound and electronic fetal heart rate monitoring 1, 2

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Management of Preeclampsia

Blood Pressure Control

Severe hypertension (≥160/110 mmHg) requires urgent treatment within 15 minutes using oral nifedipine 10 mg, repeated every 20 minutes to maximum 30 mg, targeting systolic BP 110-140 mmHg and diastolic BP 85 mmHg. 2, 4

• Alternative for severe hypertension: IV labetalol 20 mg bolus, then 40 mg after 10 minutes if needed, followed by 80 mg every 10 minutes to maximum 220 mg 2
• For non-severe hypertension (≥140/90 mmHg), treat with oral antihypertensives targeting diastolic BP 85 mmHg and systolic BP 110-140 mmHg 2

Critical Medication Contraindications

• ACE inhibitors, ARBs, and direct renin inhibitors are absolutely contraindicated due to severe fetotoxicity causing renal dysgenesis 2, 4
• Avoid sublingual nifedipine due to risk of precipitous blood pressure drops 2
• Do not combine IV magnesium with calcium channel blockers due to myocardial depression risk 2
• Diuretics are contraindicated as they further reduce plasma volume and worsen uteroplacental perfusion 2, 4

Seizure Prophylaxis with Magnesium Sulfate

Magnesium sulfate must be administered for convulsion prophylaxis in women with preeclampsia who have severe hypertension, proteinuria with severe hypertension, or neurological signs/symptoms. 1, 2

• Continue magnesium sulfate for 24 hours postpartum 2
• Monitor for magnesium toxicity: maintain patellar reflexes (knee jerk), respiratory rate ≥16 breaths/min, and urine output ≥100 mL in 4 hours preceding each dose 5
• Therapeutic serum magnesium levels range from 3-6 mg/100 mL (2.5-5 mEq/L); reflexes diminish >4 mEq/L and may be absent at 10 mEq/L where respiratory paralysis occurs 5
• Have injectable calcium salt immediately available to counteract magnesium toxicity 5

Maternal Monitoring Protocol

• Monitor blood pressure every 4 hours while awake (more frequently if severe hypertension) 1, 2
• Perform clinical assessment including evaluation for clonus, neurological symptoms, visual disturbances, and epigastric/right upper quadrant pain 1, 2
• Repeat laboratory tests at least twice weekly or more frequently if clinical deterioration occurs 1, 2

Fluid Management

• Strictly limit total fluid intake to 60-80 mL/hour to prevent pulmonary edema 2
• Aim for euvolemia; avoid "running dry" as this increases acute kidney injury risk 2

Fetal Surveillance

• Perform serial ultrasound assessments for fetal biometry, amniotic fluid volume, and umbilical artery Doppler to monitor for intrauterine growth restriction 1, 2
• Continue electronic fetal heart rate monitoring to assess fetal well-being 2, 4

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Timing of Delivery

Delivery is the definitive treatment for preeclampsia and should occur at 37 weeks' gestation or earlier if any severe features develop. 1, 2

Mandatory Immediate Delivery Indications

• Repeated episodes of severe hypertension despite treatment with 3 classes of antihypertensives 1, 2, 3
• Progressive thrombocytopenia 1
• Progressively abnormal liver or renal function tests 1, 3
• Pulmonary edema 1, 3
• Severe intractable headache, repeated visual scotomata, or eclamptic seizures 1, 3
• Non-reassuring fetal status 1, 2, 3
• Placental abruption 2

Gestational Age Considerations

• If gestation <34 weeks and delivery can be delayed, administer corticosteroids for 48 hours to accelerate fetal lung maturation 2

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Management of Eclampsia (Seizures)

Magnesium sulfate is the definitive first-line anticonvulsant for eclamptic seizures and must be administered immediately. 3

Immediate Actions for Eclamptic Seizure

• Administer magnesium sulfate immediately as first-line anticonvulsant 3
• Treat severe hypertension (≥160/110 mmHg) within 15 minutes to prevent maternal cerebral hemorrhage using oral nifedipine as preferred first-line agent 3
• Assess for HELLP syndrome (hemolysis, elevated liver enzymes, low platelets <100,000/μL) which carries 3.4% maternal mortality; epigastric or right upper quadrant pain is the hallmark symptom 3
• Perform electronic fetal heart rate monitoring to assess fetal well-being 3
• Deliver after maternal stabilization, as delivery is the definitive treatment for eclampsia 3

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Postpartum Management

Women with preeclampsia remain at high risk for complications including eclamptic seizures for at least 3 days postpartum and require close monitoring with blood pressure checks at least every 4 hours while awake. 1, 2

• Continue antihypertensives administered antenatally; do not cease abruptly 1, 2
• Consider treating any hypertension before day 6 postpartum, then taper antihypertensives slowly over days after days 3-6 1, 2
• Eclamptic seizures may develop for the first time in the early postpartum period 1
• Avoid NSAIDs for postpartum analgesia as they can worsen renal function in preeclampsia 1, 4

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Critical Pitfalls to Avoid

• Do not rely on blood pressure level alone to determine disease severity; serious organ dysfunction can develop at relatively mild blood pressure elevations 4, 3
• Do not use serum uric acid level or degree of proteinuria as indications for delivery 4
• Do not underestimate disease severity; all eclampsia can rapidly progress to life-threatening complications 3
• Do not use first or second trimester tests alone to predict all cases of preeclampsia; however, combination of maternal risk factors, BP, placental growth factor, and uterine artery Doppler can identify women who benefit from aspirin 1
• Do not use rule-in or rule-out tests (PlGF or sFlt-1/PlGF ratio) for routine clinical use outside of clinical trials 1