What are the guidelines for diagnosing pre-eclampsia?

Guidelines for Diagnosing Pre-eclampsia

Pre-eclampsia is defined as new-onset hypertension (≥140/90 mmHg) after 20 weeks of gestation accompanied by proteinuria, maternal organ dysfunction, or uteroplacental dysfunction. 1

Diagnostic Criteria

• Hypertension must be documented as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg, confirmed on two separate occasions or at least 15 minutes apart in cases of severe hypertension (≥160/110 mmHg) 1
• Hypertension must appear after 20 weeks of gestation in previously normotensive women 1, 2
• Proteinuria is defined as:

  • 0.3 g/24h or albumin-creatinine ratio ≥30 mg/mmol 1, 3

  • A positive dipstick test (≥1+) should prompt immediate quantification using albumin-creatinine ratio or 24-hour urine collection 1
  • When neither 24-hour collection nor protein/creatinine ratio is available, dipstick values >1 g/L (2+) provide reasonable assessment 3

Alternative Diagnostic Criteria (Without Proteinuria)

Pre-eclampsia can be diagnosed when gestational hypertension is accompanied by one or more of the following:

Maternal Organ Dysfunction

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

Uteroplacental Dysfunction

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

Assessment Protocol

• All women should be assessed for pre-eclampsia risk factors at the first antenatal visit 4
• After 20 weeks' gestation, women should be assessed for signs and symptoms of pre-eclampsia at every antenatal visit 5
• Assessment should include:
  • Blood pressure measurement (critical to use proper technique) 5
  • Urinalysis for proteinuria 5
  • Evaluation for symptoms (headache, visual disturbances, epigastric pain) 5
  • Assessment of fetal well-being 5

Laboratory Evaluation

• All women with suspected pre-eclampsia should have:
  • Full blood count 1
  • Liver enzymes 1
  • Serum creatinine 1
  • Electrolytes 1
  • Uric acid 1
  • Urinalysis and protein quantification 1

Classification of Severity

Pre-eclampsia with severe features includes:

• Severe hypertension (≥160/110 mmHg) despite treatment 1
• Progressive thrombocytopenia 1
• Progressive abnormal renal or liver enzyme tests 1
• Pulmonary edema 1
• Neurological complications 1
• Non-reassuring fetal status 1

Actions Based on Findings

New Hypertension Without Proteinuria

• Diastolic BP ≥90 and <100 mmHg: Refer for hospital assessment within 48 hours 5
• Diastolic BP ≥90 and <100 mmHg with symptoms: Refer for same-day hospital assessment 5
• Systolic BP ≥160 mmHg: Refer for same-day hospital assessment 5
• Diastolic BP ≥100 mmHg: Refer for same-day hospital assessment 5

New Hypertension With Proteinuria

• Diastolic BP ≥90 mmHg and proteinuria ≥+ on dipstick: Refer for same-day hospital assessment 5
• Diastolic BP ≥110 mmHg and proteinuria ≥+ on dipstick: Arrange immediate admission 5
• Systolic BP ≥170 mmHg and proteinuria ≥+ on dipstick: Arrange immediate admission 5
• Diastolic BP ≥90 mmHg, proteinuria ≥+ on dipstick, and symptoms: Arrange immediate admission 5

New Proteinuria Without Hypertension

• • on dipstick: Repeat assessment within one week 5
• ≥++ on dipstick: Refer for hospital assessment within 48 hours 5
• ≥+ with symptoms: Refer for same-day hospital assessment 5

Important Considerations and Pitfalls

• Hypertension before 20 weeks typically represents pre-existing or chronic hypertension, not pre-eclampsia 1
• Proteinuria is present in approximately 75% of pre-eclampsia cases but is not required for diagnosis 1, 6
• Neither serum uric acid nor the level of proteinuria should be used as an indication for delivery 1
• Repeated measurement of proteinuria for women already diagnosed with pre-eclampsia is unnecessary as the amount does not reliably predict outcomes 6
• The sFlt-1/PlGF ratio ≤38 can be used to exclude the development of pre-eclampsia in the following week when clinically suspected 1
• Pre-eclampsia can progress to a life-threatening situation in approximately two weeks from diagnosis, requiring close monitoring 5
• Women with pre-eclampsia have increased long-term risks of cardiovascular disease, stroke, diabetes mellitus, venous thromboembolic disease, and chronic kidney disease 3, 7

Monitoring Schedule

• Women with risk factors (but no indication for early specialist referral) should be seen at least once every three weeks before 32 weeks, and then at least once every two weeks until delivery 5
• Women with no risk factors should follow local protocols for antenatal care but should be informed about pre-eclampsia symptoms and how to contact healthcare professionals at all times 5