What is preeclampsia, its symptoms, and treatment?

Preeclampsia: Definition, Symptoms, and Physiology

Preeclampsia is defined as new-onset hypertension (≥140/90 mmHg) that develops at or after 20 weeks of gestation, accompanied by proteinuria (≥0.3 g/24 h) or other signs of maternal organ dysfunction, and is a major cause of maternal and fetal morbidity and mortality worldwide. 1, 2

Definition and Diagnosis

• Preeclampsia complicates 3-5% of pregnancies and is characterized by hypertension developing after 20 weeks of gestation 1, 3
• Diagnostic criteria include:
  • Blood pressure ≥140/90 mmHg (mild) or ≥160/110 mmHg (severe) 1
  • Proteinuria ≥0.3 g/24 h in a 24-hour urine collection 1, 4
  • In the absence of proteinuria, diagnosis can be made with hypertension plus any of the following: thrombocytopenia, impaired liver function, renal insufficiency, pulmonary edema, or cerebral/visual disturbances 4
• Preeclampsia typically resolves after delivery, confirming the diagnosis 2

Pathophysiology

• The exact etiology remains unclear, but involves:
  • Abnormal placentation with poor remodeling of spiral arteries leading to placental ischemia 4, 5
  • Release of anti-angiogenic factors (particularly sFlt-1) from the ischemic placenta 5
  • Widespread maternal endothelial dysfunction resulting in systemic inflammation 6
  • Reduced organ perfusion affecting multiple maternal systems 1

Clinical Manifestations

• Symptoms and signs of severe preeclampsia include:
  • Right upper quadrant/epigastric pain due to liver edema and hepatic hemorrhage 1
  • Headache and visual disturbances due to cerebral edema 1, 7
  • Hyperreflexia and clonus 1, 7
  • Convulsions in cases progressing to eclampsia 1
  • HELLP syndrome: Hemolysis, Elevated Liver enzymes, Low Platelet count 1, 4

Risk Factors

• Important risk factors include:
  • History of preeclampsia (including early-onset preeclampsia) 1
  • Intrauterine growth restriction or preterm birth 1
  • Placental abruption or fetal death 1
  • Maternal comorbid conditions (diabetes, chronic hypertension, renal disease, autoimmune diseases) 1
  • Multifetal gestation 1
  • First pregnancy 1

Screening and Prevention

• The USPSTF recommends screening for preeclampsia with blood pressure measurements throughout pregnancy 1
• For high-risk women, low-dose aspirin (60-150 mg/day) is recommended to reduce the risk of preeclampsia by 24%, preterm birth by 14%, and intrauterine growth restriction by 20% 1
• Aspirin should be started before 16 weeks of gestation for optimal prevention 6

Management

• The only definitive treatment for preeclampsia is delivery of the placenta and fetus 1, 4
• Medical management aims to:
  • Control blood pressure with antihypertensive medications (methyldopa, labetalol, or nifedipine) 7
  • Prevent seizures with magnesium sulfate 1, 8
  • Administer steroids to accelerate fetal lung maturation if <34 weeks gestation 1

Magnesium Sulfate Administration

• For severe preeclampsia or eclampsia, the total initial dose is 10-14 g of magnesium sulfate 8
• IV administration: 4-5 g in 250 mL of 5% Dextrose or 0.9% Sodium Chloride infused over 15-20 minutes 8
• Maintenance: 1-2 g/hour by constant IV infusion 8
• Therapeutic serum magnesium levels range from 3-6 mg/100 mL (2.5-5 mEq/L) 8
• Monitor for toxicity by checking patellar reflexes, respiratory rate (should be >16/min), and serum magnesium levels 8

Long-term Implications

• Women with a history of preeclampsia have increased lifetime risks of:
  • Cardiovascular disease 2, 9
  • Stroke 2
  • Diabetes mellitus 2
  • Venous thromboembolic disease 2
  • Chronic kidney disease 2
• Risk of recurrence in subsequent pregnancies is approximately 15% 9

Important Clinical Considerations

• Preeclampsia can still develop postpartum, requiring continued vigilance 2
• NSAIDs should be avoided in women with preeclampsia, especially those with acute kidney injury 2
• Blood pressure should be monitored at least every 4-6 hours for at least 3 days postpartum 2
• All women with preeclampsia should be reviewed at 3 months postpartum to ensure resolution of symptoms and laboratory abnormalities 2