Preeclampsia

Background

• Hypertensive disorder of pregnancy characterized by new-onset hypertension + proteinuria or end-organ dysfunction after 20 weeks gestation
• Affects 2-8% of pregnancies worldwide
• Leading cause of maternal and fetal morbidity and mortality
• Risk factors:
  • Nulliparity, prior preeclampsia, chronic hypertension
  • Multiple gestation, advanced maternal age (>35), obesity
  • Autoimmune disease (SLE, antiphospholipid syndrome)
  • Pregestational diabetes, chronic kidney disease
  • Family history of preeclampsia
• Pathophysiology: abnormal placental development → endothelial dysfunction → systemic vasospasm and organ damage
• Spectrum includes: preeclampsia, eclampsia (seizures), HELLP syndrome

Diagnostic Criteria (ACOG)

• Blood pressure ≥140/90 mmHg on two occasions at least 4 hours apart (or ≥160/110 once) after 20 weeks in previously normotensive patient
• PLUS one or more:
  • Proteinuria (≥300 mg/24h, protein/creatinine ratio ≥0.3, or dipstick ≥2+)
  • OR end-organ dysfunction (even without proteinuria):
    • Platelets <100,000
    • Creatinine >1.1 mg/dL (or doubling of baseline)
    • Liver transaminases >2x normal
    • Pulmonary edema
    • Cerebral or visual symptoms

Clinical Features

Preeclampsia Without Severe Features

• BP 140-159/90-109 mmHg
• Proteinuria
• May be asymptomatic or have mild edema

Preeclampsia With Severe Features (Any One)

• BP ≥160/110 mmHg (confirmed within minutes to facilitate timely treatment)
• Thrombocytopenia (<100,000)
• Impaired liver function (transaminases >2x normal, severe RUQ/epigastric pain)
• Renal insufficiency (creatinine >1.1 mg/dL)
• Pulmonary edema
• New-onset headache unresponsive to medication
• Visual disturbances (scotomata, blurred vision, photopsia)

HELLP Syndrome

• Hemolysis, Elevated Liver enzymes, Low Platelets
• Variant of severe preeclampsia; may occur without significant hypertension
• Risk of hepatic rupture, DIC, placental abruption

Differential Diagnosis

• Chronic hypertension (pre-existing before 20 weeks)
• Gestational hypertension (no proteinuria or end-organ damage)
• HELLP syndrome
• Thrombotic thrombocytopenic purpura (TTP) / hemolytic uremic syndrome (HUS)
• Acute fatty liver of pregnancy
• SLE nephritis flare
• Pheochromocytoma

Evaluation

• Blood pressure: manual measurement, correct cuff size, patient seated
• CBC with platelet count
• BMP: creatinine, uric acid (elevated in preeclampsia)
• LFTs: AST/ALT (hepatic involvement)
• LDH, haptoglobin, peripheral smear (evaluate for hemolysis / HELLP)
• Coagulation studies: PT/INR, fibrinogen, D-dimer (if concern for DIC)
• Urinalysis and urine protein/creatinine ratio
• Fetal monitoring: continuous fetal heart rate monitoring, BPP/NST
• Bedside US: fetal assessment, amniotic fluid index

Management

Severe Hypertension (BP ≥160/110) — Treat Within 30-60 Minutes

• First-line:
  • IV labetalol: 20 mg IV bolus, then 40 mg, then 80 mg q10min (max 300 mg)
  • IV hydralazine: 5-10 mg IV q20min (max 30 mg)
  • PO nifedipine (immediate release): 10-20 mg PO q20-30min (max 50 mg)
• Goal: BP 140-150/90-100 mmHg (avoid precipitous drops — risk of fetal distress)
• Avoid: ACE inhibitors, ARBs (teratogenic), nitroprusside (cyanide risk to fetus)

Seizure Prophylaxis

• Magnesium sulfate for ALL patients with severe features
  • Loading dose: 4-6g IV over 15-20 minutes
  • Maintenance: 1-2g/hr IV continuous infusion
  • Continue for 24-48 hours postpartum
• Monitor for Mg toxicity:
  • Loss of DTRs (first sign — check q1-2h)
  • Respiratory depression (hold if RR <12)
  • Therapeutic level: 4-7 mg/dL
  • Antidote: calcium gluconate 1g IV over 3 minutes

Definitive Treatment

• Delivery is the only cure
• ≥37 weeks: delivery recommended regardless of severity
• <37 weeks without severe features: expectant management with close monitoring
• <37 weeks with severe features: delivery after stabilization (give antenatal corticosteroids if 24-34 weeks)
• Mode of delivery: vaginal preferred unless obstetric indication for cesarean

Postpartum Preeclampsia

• Can occur up to 6 weeks postpartum (even without antepartum diagnosis)
• Same treatment principles: antihypertensives, magnesium if severe
• Common cause of postpartum headache and seizures

Disposition

• Preeclampsia without severe features: admit to L&D for monitoring; may manage expectantly if <37 weeks
• Preeclampsia with severe features: admit to L&D; plan for delivery after maternal stabilization
• OB consultation for all suspected cases
• Postpartum: close BP monitoring for 72 hours minimum

See Also

• Eclampsia
• HELLP syndrome
• Hypertension in pregnancy
• Placental abruption
• Postpartum emergencies

References

• ACOG Practice Bulletin No. 222: Gestational Hypertension and Preeclampsia. Obstet Gynecol. 2020;135(6):e237-e260. PMID 32443079
• Chappell LC, et al. Pre-eclampsia. Lancet. 2021;398(10297):341-354. PMID 34051884
• Sibai BM. Diagnosis, prevention, and management of eclampsia. Obstet Gynecol. 2005;105(2):402-410. PMID 15684172