What are the diagnostic criteria for pre-eclampsia?

Pre-eclampsia Diagnostic Criteria

Pre-eclampsia is diagnosed when new-onset hypertension (≥140/90 mmHg) develops after 20 weeks of gestation in a previously normotensive woman, accompanied by either proteinuria (≥0.3 g/24h) OR evidence of maternal organ dysfunction OR uteroplacental dysfunction. 1

Core Diagnostic Requirements

Hypertension Criteria

• Systolic BP ≥140 mmHg and/or diastolic BP ≥90 mmHg confirmed on two separate occasions at least 15 minutes apart (or immediately in cases of severe hypertension ≥160/110 mmHg) 1
• Hypertension must appear after 20 weeks of gestation in women who were previously normotensive 1
• Hypertension appearing before 20 weeks typically represents chronic hypertension, not pre-eclampsia 1

Proteinuria Criteria (When Present)

• ≥0.3 g protein in 24-hour urine collection 1
• Albumin-creatinine ratio ≥30 mg/mmol on a random urine sample 1
• Dipstick ≥1+ should prompt immediate quantitative evaluation using albumin-creatinine ratio or 24-hour collection 1
• An albumin-creatinine ratio <30 mg/mmol reliably excludes proteinuria 1

Critical Update: Proteinuria No Longer Required

Proteinuria is present in only approximately 75% of pre-eclampsia cases and is NOT required for diagnosis. 1 This represents a major shift from older definitions that mandated proteinuria. 2, 3

Alternative Diagnostic Criteria (Without Proteinuria)

When gestational hypertension occurs without proteinuria, pre-eclampsia can still be diagnosed if accompanied by any of the following: 1

Maternal Organ Dysfunction:

• Acute kidney injury: serum creatinine ≥1.1 mg/dL or doubling of baseline creatinine 1
• Hepatic dysfunction: liver transaminases ≥2 times upper limit of normal 1
• Hematological dysfunction: thrombocytopenia <100,000/microliter 1
• Neurological complications: severe headache, visual disturbances, eclampsia 1
• Pulmonary edema 1

Uteroplacental Dysfunction:

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

Severe Pre-eclampsia Features

Pre-eclampsia with severe features includes any of the following: 1

• Severe hypertension ≥160/110 mmHg despite treatment with multiple antihypertensives 1
• Progressive thrombocytopenia 1
• Progressive abnormal renal or liver enzyme tests 1
• Pulmonary edema 1
• Neurological complications (severe headache, visual disturbances, seizures) 1
• Non-reassuring fetal status 1

Common Pitfalls to Avoid

• Do NOT use serum uric acid levels as an indication for delivery 1
• Do NOT use the level of proteinuria to determine timing of delivery 1
• Hyper-reflexia is nonspecific and no longer recommended as a diagnostic criterion 1
• Edema is not predictive and should not be used diagnostically 4
• Eclampsia can occur without severe hypertension: 34% of eclamptic women had maximum diastolic BP ≤100 mmHg 4

Timing Considerations

• New hypertension before 32 weeks carries a 50% chance of developing pre-eclampsia 4
• New hypertension at 24-28 weeks is particularly predictive of severe pre-eclampsia 4
• Pre-eclampsia can progress to life-threatening complications in approximately two weeks from diagnosis 1

Biomarker for Risk Stratification

• sFlt-1/PlGF ratio ≤38 can be used to exclude the development of pre-eclampsia in the following week when clinically suspected 1

Differential Diagnosis

The differential diagnosis must include: 1

• Gestational hypertension without proteinuria (hypertension alone after 20 weeks)
• Chronic hypertension (hypertension present before pregnancy or before 20 weeks)
• Superimposed pre-eclampsia (development of pre-eclampsia features in the context of pre-existing hypertension or proteinuria)