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

• Preeclampsia is most likely caused by narrowed uteroplacental spiral artery formation and abnormal placentation, which lead to placental hypoperfusion and ischemia. These changes trigger the release of antiangiogenic factors that cause widespread maternal vasoconstriction (eg, hypertension), endothelial cell damage (eg, third spacing with edema and weight gain), and end-organ damage (eg, headache).
• This results in peripheral edema and relative intravascular volume depletion.
• 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 Pregnancy#Renal system.

Treatment

Antihypertensives in pregnancy

Antihypertensives for urgent blood pressure control in pregnancy

• Parenteral labetalol (avoid in patients with contraindications to β-blockers)
• Nifedipine (immediate release)
• Parenteral hydralazine

Common oral antihypertensives in pregnancy

• Labetalol
• Nifedipine (extended release)
• Methyldopa

Magnesium sulfate for seizure prophylaxis

• Indications
  • Eclampsia
  • HELLP syndrome
  • Preeclampsia with severe features
• Administration: magnesium sulfate (IV or IM)
  • Contraindicated in patients with myasthenia gravis
  • Should be administered with care in patients with renal insufficiency
• Monitoring
  • Monitor all patients for signs of hypermagnesemia (e.g., decreased deep tendon reflexes, respiratory depression).
  • Signs of hypermagnesemia: Administer calcium gluconate (see “Hypermagnesemia” for clinical features and more information on management of hypermagnesemia).

Aspirin for preeclampsia prophylaxis

• Indications
  • ≥ 1 high-risk feature or ≥ 2 moderate-risk factors for preeclampsia.
• Regimen
  • Initiate low-dose aspirin between 12–20 weeks' gestation (optimally before 16 weeks)