Transaminases and platelets mark the pre-eclamptic woman who develops PRES

Design

systematic review and random-effects meta-analysis of 28 observational studies

Population

women with pre-eclampsia or eclampsia; literature searched to March 2025

Primary outcome

pooled incidence of PRES, with associated clinical, laboratory and imaging features

Effect

ALT mean difference 35.88 IU/L, AST 48.69 IU/L, platelets −31.15 × 10⁹/L; pooled incidence 38.68% (95% CI 29.63 to 48.59), I² = 98.5%

Posterior reversible encephalopathy syndrome is the lesion behind much of the neurology of severe pre-eclampsia and eclampsia, and it is under-recognised because headache and visual disturbance are near-universal in these women anyway. A systematic review pooled 28 observational studies searched to March 2025, with a random-effects model.

Women with PRES had markedly higher liver enzymes — mean difference 35.88 IU/L for ALT and 48.69 IU/L for AST — and lower platelet counts, mean difference −31.15 × 10⁹/L. Total bilirubin was also raised. Maternal mortality risk was higher but did not reach significance (RR 4.06), and stillbirth and preterm birth showed no significant association. Imaging most often involved the frontal (43.05%) and temporal (20.33%) lobes. The pooled incidence of PRES was reported as 38.68% (95% CI 29.63 to 48.59) with I² of 98.5%.

The usable finding is the direction of the laboratory associations, which overlap almost exactly with the HELLP picture. In a woman with pre-eclampsia and neurological symptoms whose transaminases are climbing and platelets falling, this supports imaging rather than attributing the headache to the blood pressure — particularly where magnesium is already running and the symptoms are not settling.

• Repeat liver function and platelets in any pre-eclamptic woman with new or persisting neurological symptoms.
• Do not treat a normal fundoscopy or a settling blood pressure as reassurance about the brain.
• Consider imaging where visual symptoms, altered consciousness or seizures persist despite magnesium.
• Frontal and temporal involvement is common enough that a posterior-only reading of the scan will miss cases.
• Delivery and blood pressure control remain the treatment — imaging changes surveillance, not the plan.

Why it matters

It gives a laboratory prompt for imaging in a setting where neurological symptoms alone are too common to act on.

Don't overread it

The 38.68% figure is not the chance that your next pre-eclamptic patient has PRES — most included studies imaged only symptomatic women.

The statistics, in plain English

An I² of 98.5% means almost all the variation between studies is real difference rather than chance, so the pooled incidence of 38.68% is not a number to quote to a patient — it is an average of populations selected in incompatible ways, mostly women who were scanned because they already had symptoms. The laboratory mean differences are more robust because they compare women within the same studies. The mortality risk ratio of 4.06 without significance means the data are too sparse to settle the question either way.

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