What are the diagnostic criteria for preeclampsia with severe features?

Diagnostic Criteria for Preeclampsia with Severe Features

Preeclampsia with severe features is diagnosed when gestational hypertension (BP ≥140/90 mmHg after 20 weeks) occurs with any of the following: severe hypertension (BP ≥160/110 mmHg), thrombocytopenia (<100,000/μL), elevated liver enzymes (≥2x upper limit of normal), renal insufficiency (creatinine >1.1 mg/dL or doubling of baseline), pulmonary edema, or new-onset cerebral/visual symptoms.

Blood Pressure Criteria

The foundation requires new-onset hypertension at or after 20 weeks of gestation 1:

• Severe hypertension: Systolic BP ≥160 mmHg and/or diastolic BP ≥110 mmHg
• This severe BP threshold alone qualifies as a severe feature and should be confirmed within 15 minutes 1
• For less severe elevations (140-159/90-109 mmHg), BP should be repeated over several hours 1

Maternal Organ Dysfunction Criteria

Any ONE of the following constitutes severe features 1:

Hematologic

• Thrombocytopenia: Platelet count <100,000/μL 2
• Hemolysis (as part of HELLP syndrome) 1

Hepatic

• Elevated liver enzymes: AST or ALT ≥2 times the upper limit of normal 1, 2
• Persistent right upper quadrant or epigastric pain unresponsive to medication 2

Renal

• Serum creatinine >1.1 mg/dL or doubling of baseline creatinine in the absence of other renal disease 1
• Progressive renal insufficiency 2

Neurologic

• New-onset persistent headache unresponsive to medication 1
• Visual disturbances (scotomata, cortical blindness, retinal vasospasm) 2
• Altered mental status 1

Pulmonary

• Pulmonary edema 2

Fetal

• Fetal growth restriction in the context of new-onset hypertension (though this remains somewhat controversial) 1

Critical Clinical Points

Proteinuria is NOT required for the diagnosis of preeclampsia or severe features—it is present in only approximately 75% of cases 1. The diagnosis relies on hypertension plus evidence of maternal organ dysfunction.

The term "severe preeclampsia" has been deliberately replaced with "preeclampsia with severe features" because the disease can become life-threatening at any stage, and classifying it as "mild" can be dangerously misleading 1.

Laboratory Evaluation

When preeclampsia with severe features is suspected, obtain 1:

• Complete blood count (hemoglobin and platelet count)
• Liver enzymes (AST, ALT, LDH) and liver function tests
• Serum creatinine and electrolytes
• Urine protein assessment (dipstick, protein-to-creatinine ratio, or 24-hour collection)

Management Implications

Delivery is the definitive treatment for preeclampsia with severe features, particularly at or beyond 34 weeks of gestation 3. Patients should receive intravenous magnesium sulfate for seizure prophylaxis 3. The presence of severe features indicates high risk for rapid maternal clinical deterioration and necessitates urgent obstetric evaluation for delivery timing 3.

The threshold of liver enzymes ≥2x upper limit of normal is based on expert consensus rather than robust outcome data—research suggests this threshold may not independently predict adverse outcomes when adjusted for gestational age at delivery 4. However, it remains the accepted diagnostic criterion and should prompt delivery consideration 1.