Harvey's Garden

Hypertensive pregnancy disorders

Properties2
tags—
aliasesEclampsia, Preeclampsia, HELLP syndrome, Pre-eclampsia

5 min read

Definition

  • Chronic Hypertension (CHTN)
    • Baseline SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg present before pregnancy or diagnosed < 20 wks gestation.
    • Persists > 12 wks postpartum.
  • Gestational Hypertension (gHTN)
    • New-onset SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg at ≥ 20 wks gestation in a previously normotensive pt.
    • No proteinuria and no severe features.
    • Resolves < 12 wks postpartum.
  • Preeclampsia (PEC) without Severe Features
    • New-onset SBP ≥ 140 mmHg or DBP ≥ 90 mmHg on 2 occasions ≥ 4 hrs apart at ≥ 20 wks gestation PLUS:
    • Proteinuria: ≥ 300 mg/24-hr urine, Urine Protein/Creatinine (UPCR) ratio ≥ 0.3, or urine dipstick ≥ 2+.
  • Preeclampsia with Severe Features (PEC w/ SF)
    • Meets PEC criteria PLUS ≥ 1 of the following severe features:
      • Severe HTN: SBP ≥ 160 mmHg or DBP ≥ 110 mmHg on 2 occasions ≥ 15 min apart.
      • Thrombocytopenia: Plt < 100,000/µL.
      • Renal Insufficiency: Serum Cr > 1.1 mg/dL or doubling of baseline Cr.
      • Impaired Liver Function: Transaminases (AST/ALT) > 2x upper limit of normal or severe persistent RUQ/epigastric pain. c2
      • Pulmonary Edema.
      • Cerebral/Visual Symptoms: Severe persistent headache, scotomata, altered mental status.
    • Note: Degree of proteinuria is NOT a severe feature in current ACOG guidelines.
    • Can present up to 6 weeks after delivery c
  • Chronic HTN with Superimposed Preeclampsia
    • Pt w/ pre-existing CHTN who develops new-onset proteinuria, sudden worsening of control, or severe features at ≥ 20 wks gestation.
  • Eclampsia
    • New-onset generalized tonic-clonic seizures in a pt with preeclampsia without other neurologic etiology.
  • HELLP Syndrome
    • Severe variant of PEC defined by:
      • Hemolysis: Microangiopathic hemolytic anemia (MAHA) w/ schistocytes, ↑ indirect bili, ↑ LDH (> 600 U/L), low haptoglobin.
      • Elevated Liver enzymes: AST/ALT > 2x normal.
      • Low Platelets: Plt < 100,000/µL.

Epidemiology

Etiology

Pathophysiology

  • Two-Wave Trophoblast Invasion:
    • First wave (weeks 0–12): Endovascular trophoblasts invade decidual segments of maternal spiral arteries.
    • Second wave (weeks 16–20): Trophoblasts invade myometrial segments, converting high-resistance/low-flow vessels into low-resistance/high-flow channels.
  • Abnormal Placentation: Defective second wave trophoblast invasion → failure of spiral artery remodeling → persistent narrow, high-resistance vessels → placental ischemia.
  • Antiangiogenic Release: Hypoxic placenta releases sFlt-1 and Soluble Endoglin (sEng) → neutralizes VEGF and PlGF.
  • Systemic Endothelial Dysfunction:
    • Vasospasm & HTN: ↓ PGI2/NO, ↑ Thromboxane A2 & Angiotensin II sensitivity.
    • Capillary Leak: Proteinuria, generalized edema, pulmonary edema.
    • End-Organ Damage:
      • Renal: Glomerular endotheliosis (capillary swelling, ↓ GFR, proteinuria).
      • CNS: Loss of autoregulation → vasogenic cerebral edema (PRES-like pattern) → seizures.
      • Hepatic: Sinusoidal fibrin deposition → periportal necrosis → Glisson capsule distension/rupture.
      • Hematologic: Microvascular shear stress → schistocytes (MAHA) + platelet consumption (accelerated platelet adhesion and aggregation at sites of injured endothelium)

Clinical features

Diagnostics

  • BP Measurement: ≥140/90 on 2 occasions ≥4 hrs apart (or ≥160/110 once confirmed).
  • Proteinuria Assessment:
    • Screen: Urine Dipstick (≥1+).
    • Confirm: Urine Protein:Creatinine Ratio (UPCR) ≥0.3 OR 24-hr urine protein >300 mg (Gold Standard).
  • Key Labs (End-Organ Check):
    • CBC: Plt <100k (Thrombocytopenia).
    • CMP: Cr >1.1 (or doubling), AST/ALT >2x upper limit normal. c
    • Smear: Assess for hemolysis (schistocytes) if HELLP suspected.
  • Fetal Assessment: NST, BPP, Umbilical Artery Doppler (risk of IUGR/oligohydramnios).

Differential diagnostics

FeatureChronic HTNGestational HTNPreeclampsiaEclampsia
Onset< 20 wks≥ 20 wks≥ 20 wks≥ 20 wks
Defining FeatureHTN that predates pregnancy or starts before 20 weeks.New HTN w/o proteinuria or signs of end-organ damage.New HTN w/ proteinuria OR signs of end-organ damage (↑Cr, ↑LFTs, low platelets, HA, visual sx).Preeclampsia + new-onset tonic-clonic seizures.
ManagementMonitor; Tx if severe (Labetalol, Nifedipine).Monitor for progression to preeclampsia.Delivery is the cure. MgSO4 for seizure prophylaxis in severe cases.1. MgSO4 (to control seizures)
2. Delivery (once stable).
Key ComplicationSuperimposed preeclampsia.Progression to preeclampsia.HELLP syndrome, eclampsia, placental abruption.Stroke, status epilepticus, maternal death.
PostpartumHTN persists.HTN resolves.HTN resolves.HTN resolves.

Treatment

  • Antihypertensive Therapy (Severe Range BP ≥ 160/110 mmHg)
    • Goal: SBP 140-150 / DBP 90-100 to prevent maternal stroke while maintaining uteroplacental perfusion.
    • First-line Acute IV/Oral Agents:
      • IV Labetalol: Non-selective β-blocker w/ α1-blocking activity. Avoid in bradycardia or asthma.
      • IV Hydralazine: Direct vasodilator. Risk of reflex tachycardia and profound hypotension. c
      • Oral Immediate-Release Nifedipine: CCB. Avoid if vomiting/unable to tolerate PO.
    • Maintenance Antihypertensives (for CHTN/long-term control):
      • Labatetalol, Long-acting Nifedipine, Methyldopa.
      • Contraindicated: ACEi, ARBs, Direct Renin Inhibitors, Mineralocorticoid Receptor Antagonists (teratogenic / fetal renal agenesis).
  • Seizure Prophylaxis & Treatment
    • Magnesium Sulfate (MgSO4): Indicated for PEC w/ severe features, HELLP, and Eclampsia.
      • Dosing: 4-6 g IV loading dose followed by 1-2 g/hr IV maintenance.
      • MgSO4 Toxicity Monitoring: c
        • Loss of Deep Tendon Reflexes (DTRs): 8-10 mEq/L (earliest sign).
        • Respiratory Depression: 12-15 mEq/L.
        • Cardiac Arrest: > 15 mEq/L.
      • Antidote for Mg Toxicity: IV Calcium Gluconate (10 mL of 10% solution).
  • Timing & Mode of Delivery (Definitive Cure)
    • Gestational HTN & PEC w/o severe features: Deliver at 37 0/7 wks gestation.
    • PEC w/ Severe Features / HELLP:
      • ≥ 34 0/7 wks gestation: Deliver upon stabilization.
      • < 34 0/7 wks gestation: Hospitalize; administer antenatal corticosteroids (Betamethasone) for fetal lung maturity; deliver if maternal/fetal deterioration occurs.
    • Eclampsia: Emergency stabilization (Airway, Oxygen, MgSO4, IV antihypertensives) -> Immediate delivery regardless of gestational age once mother is stable.
    • Mode of Delivery: Vaginal delivery is preferred unless obstetric indications (e.g., nonreassuring fetal status, breech) mandate C-section.

Complications

  • Maternal:
    • Placental Abruption (Abruptio Placentae).
    • DIC (Disseminated Intravascular Coagulation).
    • Pulmonary Edema.
    • Acute Kidney Injury (AKI) / Acute Tubular Necrosis.
    • Cerebrovascular Accident (Stroke) / Intracranial Hemorrhage. c
    • Hepatic Rupture / Subcapsular Hematoma.
  • Fetal / Neonatal:
    • Fetal Growth Restriction (FGR) secondary to chronic uteroplacental insufficiency.
    • Oligohydramnios.
    • Prematurity (iatrogenic or spontaneous).
    • Preterm delivery
    • Intrauterine Fetal Demise (IUFD).
    • Neonatal Respiratory Distress Syndrome (RDS).

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