Preeclampsia

Background

• New-onset hypertensive disorder related to pregnancy, resulting in significant maternal morbidity and mortality worldwide
• Preeclampsia and eclampsia are diagnosed after 20wks gestation and <4wk post-partum
  • May occur sooner with gestational trophoblastic disease
  • Only 10% of cases occur prior to 34wk
• Pathogenesis: Abnormalities in placental arterial vasculature, including spiral arteries, in early pregnancy can lead to relative hypoperfusion of placenta; subsequent release of growth factors lead to maternal endothelial dysfunction causing systemic hypertension

Risk Factors

• Past history of preeclampsia
• First pregnancy
• Family history of preeclampsia
• Preexisting medical conditions:
  • Pregestational diabetes
  • Blood pressure ≥130/80 mm Hg at the first prenatal visit
  • Antiphospholipid antibodies
  • Body mass index ≥26.1
  • Chronic kidney disease
  • Twin pregnancies
  • Advanced maternal age

Clinical Features

• Headache, new-onset
• Edema
• RUQ or epigastric pain
• Elevated BP
• With increasing severity; pulmonary edema, visual changes, and altered mental status can develop

Differential Diagnosis

3rd Trimester/Postpartum Emergencies

• Acute fatty liver of pregnancy
• Amniotic fluid embolus
• Chorioamnionitis
• Eclampsia
• HELLP syndrome
• Mastitis
• Peripartum cardiomyopathy
• Postpartum endometritis (postpartum PID)
• Postpartum headache
• Postpartum hemorrhage
• Preeclampsia
• Resuscitative hysterotomy
• Retained products of conception
• Septic abortion
• Uterine rupture

Hypertension

• Hypertensive emergency
• Stroke
• Sympathetic crashing acute pulmonary edema
• Ischemic stroke
• Intracranial hemorrhage
• Preeclampsia/Eclampsia
• Autonomic dysreflexia
• Scleroderma renal crisis
• Acute glomerulonephritis
• Type- I myocardial infarction
• Volume overload
• Urinary obstruction
• Drug use or overdose (e.g stimulants, especially alcohol, cocaine, or Synthroid)
• Renal Artery Stenosis
• Nephritic and nephrotic syndrome
• Polycystic kidney disease
• Tyramine reaction
• Cushing's syndrome
• Obstructive sleep apnea
• Pheochromocytoma
• Hyperaldosteronism
• Hyperthyroidism
• Anxiety
• Pain
• Oral contraceptive use

Evaluation

Work-Up

Note that all lab findings must not be explained by an pre-existing condition in order to be relevant for diagnosis of preeclampsia

• CBC
  • Thrombocytopenia suggests severe disease
• Chemistry
  • Elevated creatinine suggests severe disease
• LFTs
  • AST/ALT elevation suggests severe disease
• Urinalysis
  • Proteinuria (see diagnostic criteria)
• Baseline Mg level
• LDH
  • Elevation suggests microangiopathic hemolysis
• Uric acid level
  • Often elevated in preeclampsia but is not counted as a severe feature

ACOG Diagnostic Criteria

• In 2013, ACOG has decided to remove proteinuria from the definition of severity of preeclampsia but it is still part of the diagnosis
• See ACOG practice bulletin 222, Gestational Hypertension and Preeclampsia, for recommendations on diagnosis
• Diagnosis is based on blood pressure and proteinuria, OR based on blood pressure and presence of end-organ dysfunction (severe features) without proteinuria
  • Although most patients will have proteinuria, lack of it does not preclude diagnosis
  • Presence of "severe features" (see below) signify end organ dysfunction 
• Preeclampsia superimposed upon chronic hypertension: Similar criteria to preeclampsia, with acutely worsening blood pressure superimposed upon baseline, along with proteinuria and/or end-organ dysfunction

Blood Pressure

• Hypertension: Systolic ≥140 mmHg or diastolic ≥90 mmHg on 2 occasions at least 4 hours apart, after 20 weeks gestation with previously normal BPs
• Severe range hypertension: Systolic ≥160 mmHg or diastolic ≥110 mmHg acutely requiring emergent blood pressure decreases

Proteinuria

• Proteinuria ≥300mg in a 24-hour urine collection
• Spot (one-time) protein(mg/dL)/creatinine(mg/dL) ratio ≥0.3
• 2+ on urine dipstick (not preferred; use if no quantitative measurement is unavailable)

Severe Features

• Systolic BP ≥160 or diastolic BP ≥110, 2 occasions, 4 hours apart, while on bed rest (unless antihypertension meds were started before this time)
• Thrombocytopenia platelets <100,000/mL
• Progressive renal insufficiency (creatinine >1.1mg/dL or doubling of creatinine concentration in absence of renal disease)
  • Reduced urine output < 30 cc/hr may indicate severe disease
• Elevated Liver function tests (2x normal concentration), severe persistent RUQ/epigastric pain unresponsive to medications and no alternative diagnosis
• Pulmonary edema
• New onset headache resistant to medications, or visual disturbance (scotomata, blurry vision, loss of vision)
• Note that massive proteinuria is not currently a criteria for severe feature

Management

BP Control

• For pregnant women with chronic hypertension, BP should be maintained between systolic 120-160mmHg and diastolic 80-105mmHg
• Either labetalol or hydralazine can be used for initial control. Maximize the dose of each drug before adding on additional therapy.

Urgent BP Control

• Labetalol
  • Option 1: Initial 10-20mgIV; then doses of 20-80mg IV q20-30min PRN to total of 300mg
  • Option 2: Constant IV infusion of 1-2mg/min
• Hydralazine
  • Option 1: 5mg IV or IM, then 5-10mg IV q20-40min PRN to total of 30mg
  • Option 2: Constant infusion 0.5-10mg/hr
• Nifedipine
  • Option 1: 10-20mg PO, repeat in 30 minutes PRN; then 10-20mg q 2-6 hours

Oral Antihypertension

These meds can be used safely to control hypertension of pregnancy

• Labetalol
  • Option 1: 200-2400mg/d in two to three divided doses
• Nifedipine ER
  • Option 1: 30-120mg/d
• Methyldopa
  • Option 1: 0.5-3 g/d in two to three divided doses
• Thiazide diuretics - used as second line agent
• ACE Inhibitor/ARB - CONTRAINDICATED IN PREGNANCY DUE TO TERATOGENICITY

Delivery Timing

• Preeclampsia without severe features, delivery at 37 weeks
• Preeclampsia with severe features
  • Before fetal viability, delivery after maternal stabilization, expectant management is not recommended
  • Viable fetus at 33 6/7 weeks or less may delay delivery for 48 hours of corticosteroids if maternal and fetal conditions remain stable with any of the following:
    • PPROM
    • Labor
    • Low platelet count <100,000mL
    • Persistent abnormal LFT(2x normal concentration)
    • IUGR<5%
    • Severe oligohydramnios (AFI<5cm)
    • Reversed end diastolic flow on umbilical artery Doppler studies
    • New onset renal dysfunction or increasing renal dysfunction.
• Do not delay delivery after initial maternal stabilization regardless of gestational age for women with PreE with severe features complicated by any of the following:
  • Uncontrollable severe hypertension
  • Eclampsia
  • Pulmonary edema
  • Placental abruption
  • Disseminated intravascular coagulation
  • Evidence of nonreassuring fetal status
  • Intrapartum fetal demise

Prevention

• The USPSTF recommends the use of low-dose aspirin (81mg/d) as preventive medication after 12 weeks of gestation in women who are at high risk for preeclampsia. ( B recommendation)

• Per ACOG Task Force: For women with prior preeclampsia that led to delivery before 34 weeks of gestation or occurring in more than one pregnancy, offer daily low-dose aspirin (81mg or less) late in the first trimester.

Seizure Prophylaxis

• Magnesium
  • Option 1: Load 4-6 grams 10% magnesium sulfate in 100ml solution IV over 20 minutes, then continuous infusion of Magnesium sulfate maintenance 1-2 grams/hour
  • Option 2: Magnesium sulfate 10 grams of 50% solution IM (5 grams in each buttock) if no IV accessMagnesium sulfate on infusion pump
• Despite category D label, can be safely used for <48h to allow administration of betamethasone prior to preterm delivery
• Contraindications: pulmonary edema, renal failure, myasthenia gravis
• Observe for loss of reflexes, respiratory depression

Disposition

• Consult with OB/GYN regarding discharge versus admission
  • Some cases of mild preeclampsia may be candidates for outpatient therapy
    • Close follow up and return precautions is key
    • Repeat lab tests 1-2x per week (platelet count, creatinine, AST)

See Also

• Postpartum Emergencies
• Eclampsia

External Links

LITFL: Pre-eclampsia and Eclampsia