Is posterior reversible encephalopathy syndrome (PRES) common in the postpartum period?

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Last updated: September 24, 2026 • View editorial policy

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Is PRES Common Postpartum?

No, PRES is not common in the postpartum period—it is a rare but serious neurological complication that occurs in approximately 0.04-0.1% of all deliveries, though it represents one of the most frequent causes of new-onset seizures when they do occur peripartum.

Epidemiology and Context

PRES (posterior reversible encephalopathy syndrome) is an uncommon obstetric complication, but when evaluating women with new-onset neurological symptoms in the peripartum period, it becomes diagnostically important. In a tertiary hospital study, PRES accounted for 58.5% of new-onset seizures in the peripartum period 1, making it the single most common identifiable cause in that specific clinical scenario. However, this does not mean PRES itself is common—rather, when seizures occur postpartum, PRES should be high on your differential.

The condition occurs most frequently in:

  • Primiparous patients (first-time mothers)
  • Women with hypertensive disorders of pregnancy (HDP), particularly preeclampsia/eclampsia—though notably, PRES can occur in normotensive patients 2
  • The immediate postpartum period (within days of delivery) 3

Clinical Recognition

You must maintain high clinical suspicion for PRES when postpartum patients present with the classic triad: seizures, visual disturbances (including cortical blindness), and headache 3. The 2024 AHA/ASA Stroke Prevention Guidelines acknowledge that eclampsia and PRES may occur postpartum and can present atypically without preceding hypertension 4.

Key clinical features include:

  • Seizures (occur in 60-90% of cases, often as seizure clusters) 1, 5
  • Headache (severe, often refractory)
  • Visual disturbances (blurred vision to complete cortical blindness)
  • Altered mental status (confusion, encephalopathy)
  • Severe memory loss (in atypical presentations) 2

Critical Pitfall

Do not exclude PRES based on normal blood pressure. While most cases associate with severe hypertension, normotensive PRES occurs and represents a diagnostic trap 2. The rate of blood pressure increase matters more than absolute values 6.

Diagnostic Approach

MRI is the gold standard and should be obtained urgently when PRES is suspected 7, 5. Characteristic findings include:

  • Vasogenic edema in posterior cerebral hemispheres (parieto-occipital regions)
  • White matter lesions on T2-weighted or FLAIR sequences
  • ADC and DWI mapping to differentiate from early cerebral ischemia 2
  • Atypical patterns may involve temporal lobes, hippocampi, and thalami 2

The 2020 Obstetric Anaesthesia Guidelines emphasize that when neurological symptoms persist or worsen postpartum, urgent MRI should be obtained within hours, not days 8. Local protocols must enable rapid access to neuroimaging, including outside office hours.

Management Priorities

Immediate blood pressure control and seizure management are paramount 7, 5:

  1. Blood pressure stabilization: Aggressive but controlled reduction (avoid precipitous drops that could cause ischemia)
  2. Seizure prophylaxis/treatment: Short-term antiseizure medication
  3. Remove precipitating factors: Discontinue any offending agents
  4. Supportive care: ICU-level monitoring during acute phase

The 2019 NIH Preeclampsia Workshop notes that white matter lesions demonstrated on neuroimaging in severe preeclampsia may mediate long-term cognitive risks 9, underscoring the importance of early intervention.

Prognosis and Follow-up

Most patients show complete clinical and radiologic recovery within weeks when diagnosed and treated promptly 7, 5. However:

  • Mortality ranges from 10-19% if diagnosis is delayed 5
  • 40-44% may have persistent neurological deficits or residual radiologic lesions 5
  • Complications include intracranial hemorrhage, infarction, or recurrent PRES
  • Long-term cognitive function requires monitoring, as the 2019 NIH guidelines recommend longitudinal neurocognitive assessment after severe preeclampsia with neurological complications 9

Clinical Bottom Line

While PRES is rare in absolute terms among all postpartum women, it is the leading cause of new-onset seizures in the peripartum period 1. Your threshold for considering PRES must be low in any postpartum patient presenting with seizures, severe headache, or visual changes—regardless of blood pressure status. Early MRI and aggressive management are essential to prevent the 10-19% mortality and significant morbidity associated with delayed diagnosis.

References

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