What are the diagnostic features of pre-eclampsia and eclampsia?

Diagnosis of Pre-eclampsia and Eclampsia

Pre-eclampsia is diagnosed by new-onset hypertension (≥140/90 mmHg) occurring after 20 weeks of gestation combined with either proteinuria (≥300 mg/24h) OR evidence of maternal organ dysfunction, while eclampsia is defined as the occurrence of seizures in a woman with pre-eclampsia. 1, 2, 3

Core Diagnostic Criteria for Pre-eclampsia

Blood Pressure Requirements

• Systolic BP ≥140 mmHg and/or diastolic BP ≥90 mmHg confirmed on two separate occasions at least 15 minutes apart 2
• For severe hypertension (≥160/110 mmHg), confirmation should occur within 15 minutes 2
• Hypertension must be new-onset after 20 weeks of gestation in previously normotensive women 1, 2, 3
• Blood pressure measurement technique is critical, as errors have been implicated in maternal deaths 1

Proteinuria Assessment

• Significant proteinuria is defined as >0.3 g/24h or albumin-creatinine ratio ≥30 mg/mmol 2
• Dipstick testing ≥1+ should prompt immediate quantitative evaluation using albumin-creatinine ratio or 24-hour urine collection 2
• An albumin-creatinine ratio <30 mg/mmol reliably excludes proteinuria 2
• Proteinuria is present in only 75% of pre-eclampsia cases and is no longer required for diagnosis 2, 3

Alternative Diagnostic Criteria (When Proteinuria Absent)

When proteinuria is absent, pre-eclampsia can be diagnosed if gestational hypertension is accompanied by any one of the following maternal organ dysfunctions 2:

Renal dysfunction:

• Serum creatinine ≥1.1 mg/dL or doubling of baseline creatinine 2

Hepatic dysfunction:

• Elevated liver transaminases ≥2 times upper limit of normal 2, 3
• Persistent epigastric or right upper quadrant pain 3

Hematological dysfunction:

• Thrombocytopenia <100,000/microliter 2, 3

Neurological complications:

• Severe headache unresponsive to medication 1, 2
• Visual disturbances (scotomata, photophobia, blurred vision) 1, 2, 3
• Altered mental status 2

Pulmonary complications:

• Pulmonary edema 2, 3

Uteroplacental dysfunction:

• Fetal growth restriction 2
• Abnormal umbilical artery Doppler waveform analysis 2
• Reduced fetal movements 1
• Intrauterine fetal death 2

Eclampsia Diagnosis

Eclampsia is diagnosed when seizures occur in a woman with pre-eclampsia, typically presenting as generalized tonic-clonic convulsions 3, 4

Timing of Eclamptic Seizures

• 44% occur postnatally 4
• 38% occur antepartum 4
• 18% occur intrapartum 4
• Eclampsia is most common at term (≥37 weeks' gestation) 5

Screening and Assessment Protocol

Initial Risk Assessment (Before 20 Weeks)

Identify women with any of the following predisposing factors 1:

• First pregnancy (nulliparity) - RR 2.91 1, 5
• Previous pre-eclampsia - RR 7.19 1, 5
• ≥10 years since last baby 1
• Age ≥40 years - RR 1.68-1.96 1, 5
• Body mass index ≥35 - RR 1.55 1, 5
• Family history of pre-eclampsia (mother or sister) - RR 2.90 1, 5
• Booking diastolic blood pressure ≥80 mmHg 1
• Proteinuria at booking (≥+ on more than one occasion or ≥300 mg/24h) 1
• Multiple pregnancy - RR 2.93 1, 5
• Pre-existing diabetes - RR 3.56 1, 5
• Pre-existing hypertension or renal disease 1
• Presence of antiphospholipid antibodies - RR 9.72 1, 5

Monitoring After 20 Weeks

At every antenatal assessment, screen for the following signs and symptoms 1, 2:

• New hypertension (BP ≥140/90 mmHg) 1
• New proteinuria (≥+ on dipstick) 1
• Headache or visual disturbances 1
• Epigastric pain or vomiting 1
• Reduced fetal movements or small for gestational age infant 1

Monitoring Frequency

• Women with one risk factor: assess at least every 3 weeks before 32 weeks, then every 2 weeks until delivery 1, 5
• Women with no risk factors: follow standard antenatal protocols but educate about symptoms 1, 5
• Pre-eclampsia can progress to life-threatening status within approximately 2 weeks of diagnosis 1, 5, 2

Laboratory Evaluation

When pre-eclampsia is suspected, obtain 2:

• Complete blood count (assess for thrombocytopenia) 2
• Liver enzymes (AST, ALT) 2
• Serum creatinine and electrolytes 2
• Uric acid 2
• Urinalysis with protein quantification 2

Biomarker for Risk Stratification

• sFlt-1/PlGF ratio ≤38 can exclude development of pre-eclampsia in the following week when clinically suspected 2

Severity Classification

Pre-eclampsia with severe features includes 2, 3:

• Severe hypertension (≥160/110 mmHg) despite treatment with multiple antihypertensives 2
• Progressive thrombocytopenia (<100,000/μL) 2, 3
• Progressive abnormal renal function tests 2
• Progressive abnormal liver enzyme tests 2
• Pulmonary edema 2, 3
• Neurological complications (persistent headache, visual disturbances) 2, 3
• HELLP syndrome (hemolysis, elevated liver enzymes, low platelets) 3
• Non-reassuring fetal status 2

Referral Thresholds from Community Settings

New Hypertension Without Proteinuria

• Diastolic BP ≥90 and <100 mmHg: refer for hospital assessment within 48 hours 1, 2
• Diastolic BP ≥90 and <100 mmHg WITH any symptoms: refer for same-day hospital assessment 1
• Diastolic BP ≥100 mmHg OR systolic BP ≥160 mmHg: refer for same-day hospital assessment 2

New Hypertension With Proteinuria

• Diastolic BP ≥90 mmHg with proteinuria ≥+ on dipstick: refer for same-day hospital assessment 2
• Diastolic BP ≥110 mmHg OR systolic BP ≥170 mmHg with proteinuria: arrange immediate admission 2

Postpartum Pre-eclampsia Diagnosis

Postpartum pre-eclampsia is diagnosed by new-onset hypertension (≥140/90 mmHg) occurring 48 hours to 6 weeks after delivery with either proteinuria or maternal organ dysfunction 6

Postpartum Monitoring Protocol

• Measure blood pressure at least every 4 hours while awake for at least 3 days postpartum 6
• Perform urinalysis if hypertension detected 6
• Screen for symptoms: headache, visual disturbances, epigastric pain, nausea/vomiting 6
• Review all women with postpartum pre-eclampsia at 3 months to ensure normalization 6

Critical Pitfalls to Avoid

• Do not classify pre-eclampsia as "mild" versus "severe" clinically - all cases may rapidly progress to emergencies 5
• Blood pressure alone is not reliable for risk stratification - serious organ dysfunction can develop at relatively mild hypertension levels 5
• Do not use serum uric acid or proteinuria levels as indications for delivery 2
• Do not rely on hyperreflexia - this is a nonspecific finding in healthy young women and no longer recommended as diagnostic criterion 2
• Absence of antenatal care is strongly associated with eclampsia and fetal death 5
• Women with no risk factors can still develop pre-eclampsia - maintain vigilance in all pregnancies 5