What are the diagnosis criteria for pre-eclampsia in a pregnant woman?

Diagnostic Criteria for Pre-eclampsia

Pre-eclampsia is diagnosed when gestational hypertension (new-onset blood pressure ≥140/90 mmHg) develops at or after 20 weeks' gestation accompanied by either proteinuria OR any evidence of maternal organ dysfunction, with proteinuria no longer being mandatory for diagnosis. 1

Core Diagnostic Requirements

Essential Component: New-Onset Hypertension

• Blood pressure ≥140 mmHg systolic and/or ≥90 mmHg diastolic developing at or after 20 weeks' gestation in a previously normotensive woman 1, 2
• Must be documented on at least two occasions 15 minutes apart 3
• The 20-week threshold reflects when placental development should be complete; hypertension before this time represents chronic hypertension, not pre-eclampsia 2

Plus ONE of the Following:

1. Proteinuria

• ≥300 mg/24 hours on 24-hour urine collection 1
• Protein/creatinine ratio ≥30 mg/mmol (or equivalent dipstick ≥1+ on more than one occasion) 1, 3
• Present in approximately 75% of pre-eclampsia cases but not required for diagnosis 1

2. Maternal Organ Dysfunction (Any of the Following):

• Renal insufficiency: Elevated serum creatinine or other renal impairment 1, 4
• Liver involvement: Elevated liver transaminases (>twice normal values) with or without right upper quadrant/epigastric pain 1, 5
• Hematological complications: Thrombocytopenia (platelets <100,000/μL), hemolysis 1, 5
• Neurological features: New-onset headache unresponsive to medication, visual disturbances (scotomata, cortical blindness), altered mental status 1
• Pulmonary edema 5

3. Uteroplacental Dysfunction

• Fetal growth restriction in the context of new-onset gestational hypertension, even without other maternal features, should be considered pre-eclampsia given the primary placental disorder 1

Important Clinical Distinctions

HELLP Syndrome

• The combination of hemolysis, elevated liver enzymes, and low platelets is not a separate disorder but represents the severe end of the pre-eclampsia spectrum 1
• Women with HELLP features should be managed as having pre-eclampsia, with evaluation for all other manifestations 1

Superimposed Pre-eclampsia

• Occurs in approximately 25% of women with chronic hypertension 1
• Diagnosed when a woman with pre-existing hypertension develops any new maternal organ dysfunction consistent with pre-eclampsia after 20 weeks 1
• Blood pressure rises alone are insufficient for this diagnosis, as they occur normally after 20 weeks 1
• In women without baseline proteinuria, new-onset proteinuria with rising BP confirms the diagnosis 1

Critical Diagnostic Pitfalls

What NOT to Use for Diagnosis

• Hyperreflexia: Nonspecific finding present in many healthy young women; no longer included in diagnostic criteria 1
• Uric acid elevation: Should not determine timing of delivery, though it may prompt fetal growth assessment 1
• Headache alone: Multifactorial in pregnancy, but in the presence of hypertension should be considered pre-eclampsia until proven otherwise 1

Laboratory Investigations Required

When a woman presents with new-onset hypertension without dipstick proteinuria, the following tests are mandatory to exclude pre-eclampsia 1:

• Complete blood count (hemoglobin, platelets) 3
• Liver transaminases 3
• Serum creatinine 3
• Urinalysis with protein quantification (PCR or albumin:creatinine ratio) 1
• Uric acid (for prognostic assessment, not diagnosis) 1, 3

Timing Considerations

• Pre-eclampsia cannot be diagnosed before 20 weeks' gestation by definition 1, 2
• Hypertension presenting before 20 weeks indicates chronic or pre-existing hypertension 2
• This pathophysiological cutoff reflects inadequate spiral artery remodeling as the key mechanism 2

Assessment of Signs and Symptoms After 20 Weeks

At every antenatal visit after 20 weeks, actively screen for 1:

• New hypertension
• New proteinuria
• Headache or visual disturbances
• Epigastric pain or vomiting
• Reduced fetal movements or small-for-gestational-age infant