What is preeclampsia?

Preeclampsia: Definition, Diagnosis, and Clinical Implications

Preeclampsia is a pregnancy-specific syndrome characterized by new-onset hypertension after 20 weeks of gestation accompanied by maternal organ dysfunction, with or without proteinuria, that resolves after delivery. 1

Definition and Diagnostic Criteria

Preeclampsia is diagnosed when a pregnant woman develops:

1. New-onset hypertension (≥140/90 mmHg) after 20 weeks of gestation, AND
2. At least one of the following:
   • Proteinuria (≥0.3g/24h or protein:creatinine ratio ≥30mg/mmol)
   • Other maternal organ dysfunction:
     • Renal insufficiency (serum creatinine >1.1 mg/dL)
     • Liver involvement (elevated transaminases, severe right upper quadrant pain)
     • Neurological complications (headache, visual disturbances, eclampsia)
     • Hematological complications (thrombocytopenia, hemolysis)
     • Uteroplacental dysfunction (fetal growth restriction) 1, 2

Epidemiology and Impact

• Affects 2-8% of pregnancies worldwide 2
• Major cause of maternal and neonatal morbidity and mortality 3
• Accounts for approximately 25% of all infants with very low birth weight (<1500g) 1
• Leading cause of medically-indicated preterm deliveries 4

Pathophysiology

Preeclampsia develops through a two-stage process:

1. Early stage: Poor placental development/implantation in early pregnancy leading to placental ischemia
2. Late stage: Systemic maternal endothelial dysfunction resulting in organ damage 2, 5

Key pathophysiological features include:

• Abnormal spiral artery remodeling
• Placental ischemia
• Increased levels of soluble fms-like tyrosine kinase-1 (sFlt-1)
• Decreased bioavailability of vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) 5

Risk Factors

Major risk factors include:

• First pregnancy (nulliparity)
• Previous preeclampsia (7-fold increased risk)
• Pre-existing medical conditions:
  • Chronic hypertension (25% risk)
  • Pre-existing diabetes
  • Renal disease
  • Autoimmune disorders (especially antiphospholipid syndrome)
• Multiple pregnancy
• Advanced maternal age (≥40 years)
• Obesity (BMI ≥35)
• Family history of preeclampsia
• Pregnancy interval ≥10 years
• Black ethnicity 1, 2

Clinical Manifestations

Preeclampsia presents with:

• Hypertension (≥140/90 mmHg)
• Proteinuria (in approximately 75% of cases)
• Symptoms of severe disease:
  • Headache and visual disturbances (cerebral edema)
  • Right upper quadrant/epigastric pain (liver edema)
  • Nausea and vomiting
  • Reduced fetal movements 1

Severe Features of Preeclampsia

Severe preeclampsia includes:

• Severe hypertension (≥160/110 mmHg)
• HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets)
• Pulmonary edema
• Seizures (eclampsia)
• Acute kidney injury
• Placental abruption
• Fetal growth restriction 1

Monitoring and Management

1. Risk assessment should be performed early in pregnancy to identify women at increased risk 1
2. Regular monitoring of blood pressure and proteinuria throughout pregnancy
3. More frequent monitoring for high-risk women:
   • Before 32 weeks: at least every 3 weeks
   • After 32 weeks: at least every 2 weeks 1
4. Laboratory assessment for women with new-onset hypertension:
   • Complete blood count
   • Liver enzymes and function tests
   • Serum creatinine and electrolytes
   • Urinalysis and protein quantification 1

Long-term Consequences

Preeclampsia has significant long-term health implications:

• For mothers: Increased risk of cardiovascular disease, stroke, and chronic kidney disease
• For children: Higher risk of neurodevelopmental issues and cardiovascular/metabolic diseases later in life 6, 4

Prevention Strategies

For high-risk women:

• Low-dose aspirin (100-150mg daily) from 12 weeks until 36-37 weeks gestation
• Calcium supplementation (1.5-2.0g/day) for women with low calcium intake
• Healthy dietary patterns with adequate fruits, vegetables, and whole grains 2, 3

Important Clinical Considerations

• Preeclampsia can progress rapidly from mild to severe forms
• The only definitive treatment is delivery of the placenta
• Postpartum monitoring is essential as 10% of maternal deaths due to hypertensive disorders occur postpartum 1
• Women with a history of preeclampsia require long-term follow-up due to increased cardiovascular risk 6

Preeclampsia remains a significant challenge in obstetric care, requiring vigilant monitoring, timely intervention, and a thorough understanding of its multisystem effects to optimize maternal and fetal outcomes.