Harvey's Garden

Hypertensive pregnancy disorders

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Definition

  • Preeclampsia: new-onset gestational hypertension with proteinuria or end-organ dysfunction
    • Superimposed preeclampsia: preeclampsia that occurs in a patient with chronic hypertension
    • HELLP syndrome
      • A life-threatening form of preeclampsia characterized by Hemolysis, Elevated Liver enzymes, and Low Platelets
      • May occur without hypertension or proteinuria
    • Occurrence of new-onset hypertension, proteinuria, or end-organ dysfunction at < 20 weeks’ gestation is suggestive of gestational trophoblastic disease.
  • Eclampsia: new-onset seizures (tonic-clonic, focal, or multifocal) in the absence of other causes ; a convulsive manifestation of hypertensive pregnancy disorders

Epidemiology

Etiology

Pathophysiology

  • Abnormal placental development, specifically inadequate remodeling of spiral arteries, leads to placental ischemia.
  • This ischemia triggers the release of anti-angiogenic factors (like sFlt-1) and inflammatory cytokines, causing widespread maternal endothelial dysfunction.
  • The result is systemic vasoconstriction (causing hypertension), increased vascular permeability (leading to proteinuria and edema), and a pro-coagulant state.
  • Kidney
    • Third spacing (ie, intravascular volume depletion) and vasoconstriction of the renal vessels result in decreased urine production (ie, oliguria) and concentrated urine (ie, increased specific gravity) because the kidneys attempt to retain sodium and water.
    • Damage to the renal endothelium increases glomerular permeability and allows for leakage of large molecules, as evidenced by proteinuria, which is classic for preeclampsia.
    • Renal vasoconstriction causes a decreased glomerular filtration rate (GFR) and an increased serum creatinine level (above baseline). Healthy pregnant patients have decreased baseline serum creatinine levels due to blood volume expansion and increased GFR; therefore, a normal-appearing creatinine level (0.7-0.9 mg/dL) during pregnancy, as seen in this patient, typically indicates renal compromise.

Clinical features

Diagnostics

Urine studies

In the kidneys, vasospasm causes decreased renal blood flow and glomerular filtration rate, leading to minimal, concentrated urine (ie, high specific gravity) and increased serum creatinine levels.

  • 24-hour urine collection (gold standard): proteinuria (urinary protein excretion ≥ 300 mg/day)
  • Urine protein:creatinine ratio: ≥ 0.3
  • Urine dipstick: > 2+ protein
  • Increased serum creatinine level: Healthy pregnant patients have decreased baseline serum creatinine levels due to blood volume expansion and increased GFR; therefore, a normal-appearing creatinine level (0.7-0.9 mg/dL) during pregnancy typically indicates renal compromise. See Renal system.

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

  • Preeclampsia Prophylaxis
    • Low-dose aspirin for high-risk women (e.g., prior preeclampsia, chronic HTN, DM).
  • Chronic & Gestational HTN (Non-Severe)
    • Tx Goal: BP <140/90 mmHg.
    • Safe Meds: Labetalol, Nifedipine (long-acting), Methyldopa.
    • Delivery: At ≥37 weeks for gestational HTN or preeclampsia w/o severe features.
  • Preeclampsia with Severe Features / Eclampsia
    • This is an emergency. Stabilize & deliver.
    1. Seizure Prophylaxis: Magnesium Sulfate (MgSO₄).
      • Toxicity: Loss of DTRs → respiratory depression.
      • Antidote: Calcium Gluconate.
    2. Acute BP Control (if ≥160/110 mmHg):
      • IV Labetalol
      • IV Hydralazine
      • PO Nifedipine
    3. Definitive Tx: Delivery.
      • Consider corticosteroids if stable and <34 weeks.
  • Contraindicated Medications
    • ACE Inhibitors (-prils)
    • ARBs (-sartans)
    • Reason: Teratogenic (fetal renal failure).

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