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

Differential Diagnosis

3rd Trimester/Postpartum Emergencies

Hypertension

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
  • Chemistry
    • Elevated creatinine suggests severe disease
  • LFTs
    • AST/ALT elevation suggests severe disease
  • Urinalysis
  • 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[1]
  • See ACOG practice bulletin 222, Gestational Hypertension and Preeclampsia, for recommendations on diagnosis[2]
  • 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:

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)[3]
  • 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

External Links

LITFL: Pre-eclampsia and Eclampsia

References

  1. ↑ Hypertension in pregnancy: Report of the American College of Obstetricians and Gynecologists' Task Force on Hypertension in Pregnancy. Obstet Gynecol 2013; 122:1122.
  2. ↑ Gestational Hypertension and Preeclampsia: ACOG Practice Bulletin, Number 222. Obstetrics & Gynecology 135(6):p e237-e260, June 2020. | DOI:10.1097/AOG.0000000000003891
  3. ↑ http://annals.org/article.aspx?articleid=1902275
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