What are the diagnostic criteria for pre-eclampsia?

Diagnostic Criteria for Pre-eclampsia

Pre-eclampsia is defined as gestational hypertension (≥140/90 mmHg) that appears after 20 weeks of gestation, accompanied by one or more of the following: proteinuria, maternal organ dysfunction, or uteroplacental dysfunction. 1

Primary Diagnostic Criteria

• Blood pressure ≥140/90 mmHg on two separate occasions at least 4 hours apart (or within 15 minutes apart in cases of severe hypertension ≥160/110 mmHg) 1, 2
• Onset after 20 weeks of gestation in a previously normotensive woman 1, 3
• Accompanied by at least one of the following:

Proteinuria

• ≥0.3 g/24h in 24-hour urine collection 1, 2
• Protein/creatinine ratio ≥30 mg/mmol 1, 4
• Albumin/creatinine ratio ≥30 mg/mmol 1
• Positive dipstick test (≥1+) should prompt quantitative assessment 1

Maternal Organ Dysfunction (in absence of proteinuria)

• Renal: Serum creatinine ≥1.1 mg/dL or doubling of baseline 5, 1
• Hepatic: Elevated liver transaminases (≥2 times upper limit of normal) 5, 1
• Neurological: Severe headache, visual disturbances, eclampsia 1
• Hematological: Thrombocytopenia (<100,000/microliter) 5
• Pulmonary: Pulmonary edema 1

Uteroplacental Dysfunction

• Fetal growth restriction 1
• Abnormal umbilical artery Doppler waveform 1
• Intrauterine fetal death 1

Important Clinical Considerations

• The 20-week threshold is pathophysiologically significant as it reflects when placental development and remodeling of maternal spiral arteries should be complete 3
• Hypertension appearing before 20 weeks typically represents pre-existing or chronic hypertension, not preeclampsia 3
• Proteinuria is present in approximately 75% of preeclampsia cases but is not required for diagnosis 5
• The sFlt-1/PlGF ratio ≤38 can help exclude the development of preeclampsia in the following week when clinically suspected 1

Monitoring and Assessment

• All women with suspected preeclampsia should have:

  • Full blood count (hemoglobin and platelet count) 5
  • Liver enzymes (AST, ALT, LDH) and function tests (INR, bilirubin, albumin) 5
  • Serum creatinine, electrolytes, and uric acid 5
  • Urinalysis and protein quantification 5

• Blood pressure monitoring should be performed regularly, with values consistently ≥140/90 mmHg requiring treatment 5

• Urgent treatment in a monitored setting is required when BP ≥160/110 mmHg 5

Classification of Severity

• There should be no attempt to diagnose mild versus severe preeclampsia clinically as all cases may become emergencies, often rapidly 5
• Preeclampsia with severe features includes:
  • Severe hypertension (≥160/110 mmHg) despite treatment with multiple antihypertensives 5
  • Progressive thrombocytopenia 5
  • Progressive abnormal renal or liver enzyme tests 5
  • Pulmonary edema 5
  • Neurological complications 5
  • Non-reassuring fetal status 5

Differential Diagnosis

• Gestational hypertension (hypertension without proteinuria or other features) 1
• Chronic hypertension (pre-existing or appearing before 20 weeks) 1
• Preeclampsia superimposed on chronic hypertension 1

Common Pitfalls

• Neither serum uric acid nor the level of proteinuria should be used as an indication for delivery 5
• Repeated measurement of proteinuria is not recommended for monitoring disease progression, as the amount of proteinuria does not correlate well with maternal and neonatal outcomes 6
• Hyper-reflexia is a nonspecific finding often present in otherwise healthy young women and is no longer recommended as a diagnostic criterion 5
• In women with chronic kidney disease, baseline protein excretion evaluation is critical for later comparison 6