What are the differential diagnoses for a 28‑week pregnant woman presenting with headache and hypertension?

Differential Diagnoses for Headache and Hypertension at 28 Weeks Gestation

In a 28-week pregnant woman presenting with headache and hypertension, preeclampsia must be considered the primary diagnosis until proven otherwise, as headache in the presence of hypertension is a warning sign of potential eclampsia and serious maternal morbidity. 1

Primary Differential Diagnoses

1. Preeclampsia (Most Critical)

• Defined as gestational hypertension (BP ≥140/90 mmHg) at or after 20 weeks with new-onset maternal organ dysfunction, which includes neurological complications such as headache 1, 2
• Proteinuria is present in only ~75% of cases and is NOT required for diagnosis 1
• Headache with hypertension is an independent risk factor for eclamptic seizures and must trigger immediate evaluation 1
• At 28 weeks (before 34 weeks), new-onset gestational hypertension carries the highest risk of progression to preeclampsia 1

Severe features requiring immediate action include:

• Systolic BP ≥160 mmHg or diastolic BP ≥110 mmHg 1, 3
• Persistent severe headache 1
• Visual disturbances 1
• Epigastric or right upper quadrant pain 1

2. Gestational Hypertension

• New-onset hypertension after 20 weeks without features of preeclampsia 1, 3
• However, 25% of gestational hypertension cases progress to preeclampsia, with highest risk when presenting before 34 weeks 1, 2
• Headache in this context should raise suspicion for evolving preeclampsia 1

3. Chronic Hypertension with Superimposed Preeclampsia

• Approximately 25% of women with chronic hypertension develop superimposed preeclampsia 1
• Difficult to distinguish from chronic hypertension alone without baseline laboratory values 1, 2
• New-onset headache suggests superimposed preeclampsia 1

4. HELLP Syndrome

• Represents severe spectrum of preeclampsia with hemolysis, elevated liver enzymes, and low platelets 1, 4
• Should be considered part of preeclampsia, not a separate entity 1
• May present with headache and hypertension 5

5. Eclampsia (Imminent or Occurring)

• Seizures in the setting of preeclampsia 1, 2
• 34% of eclamptic women have maximum diastolic BP ≤100 mmHg, so severe hypertension is not always present 1
• Headache is a critical warning symptom 1

6. Chronic Hypertension (Pre-existing)

• Hypertension present before pregnancy or before 20 weeks gestation 1, 3, 2
• Less likely if no prior diagnosis, but possible if early pregnancy BP unknown 2
• Headache may be unrelated tension-type or migraine 1

Immediate Diagnostic Workup Required

The following tests must be performed urgently to differentiate these diagnoses and assess for maternal organ dysfunction: 1

Laboratory Evaluation:

• Complete blood count (hemoglobin, platelet count) 1
• Liver enzymes (AST, ALT, LDH) and liver function tests (INR, bilirubin, albumin) 1
• Serum creatinine, electrolytes, and uric acid 1
• Urinalysis with microscopy and protein-to-creatinine ratio or albumin-to-creatinine ratio 1

Clinical Assessment:

• Repeat BP measurement within 15 minutes if ≥160/110 mmHg 1, 3, 2
• Assess for visual disturbances, epigastric pain, hyperreflexia with clonus 1
• Fetal assessment including heart rate monitoring 1, 6

Critical Management Thresholds

Immediate hospital admission is required for: 1

• Systolic BP ≥160 mmHg or diastolic BP ≥110 mmHg 1, 3
• Diastolic BP ≥90 mmHg with new proteinuria ≥+ on dipstick AND any symptom (headache, visual changes, epigastric pain) 1
• Any headache with hypertension should be managed as preeclampsia until proven otherwise 1

Antihypertensive treatment must be initiated within 30-60 minutes when BP ≥160/110 mmHg 1, 7

Magnesium sulfate for seizure prophylaxis is indicated for: 1, 2, 5

• Preeclampsia with severe hypertension 1
• Preeclampsia with neurological symptoms (headache, visual changes) 1

Key Clinical Pitfalls

• Do not wait for proteinuria to diagnose preeclampsia – it is absent in 25% of cases 1
• Do not dismiss headache as benign – in the presence of hypertension, it must be considered preeclampsia until excluded 1
• Do not assume normal BP rules out eclampsia – one-third of eclamptic seizures occur with diastolic BP ≤100 mmHg 1
• Do not delay treatment waiting for laboratory results – severe hypertension (≥160/110 mmHg) requires immediate antihypertensive therapy 1, 7