Liver enzymes and platelets flag the eclamptic brain

Design

systematic review and random-effects meta-analysis of 28 observational studies, PRISMA 2020

Population

women with pre-eclampsia or eclampsia, searched from inception to March 2025

Primary outcome

pooled incidence of posterior reversible encephalopathy syndrome, with associated clinical and laboratory factors

Effect

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

Posterior reversible encephalopathy syndrome (PRES) is the imaging correlate behind much of the headache, visual disturbance and seizure activity in severe pre-eclampsia and eclampsia, and it has never been easy to predict at the bedside. A systematic review pooled 28 studies to ask which clinical and laboratory features travel with it.

The pooled incidence — 38.68% — is the least useful number in the paper, because heterogeneity was almost total. What survives across the studies is a biochemical pattern. Women who developed PRES had substantially higher transaminases and lower platelet counts than those who did not, with alanine aminotransferase a mean 35.88 IU/L higher, aspartate aminotransferase 48.69 IU/L higher and platelets about 31 × 10⁹/L lower. Bilirubin was also raised. Imaging most often involved the frontal and temporal lobes rather than the occipital distribution the name implies.

In practice this pulls the PRES question towards tests you have already sent. A pre-eclamptic woman with neurological symptoms and a deranged liver panel and falling platelets is a different proposition from one with the same symptoms and normal bloods, and in a unit where an urgent magnetic resonance scan means a transfer, that distinction is what decides whether the transfer happens. The authors make the point explicitly for resource-limited settings, which is most of Indian obstetric practice outside the metros.

• Send liver enzymes and a platelet count on any pre-eclamptic woman who reports headache or visual change, not only those with severe features by blood pressure.
• Treat frontal or temporal signal change on imaging as compatible with PRES — the occipital pattern is not required.
• Document the neurological examination at the time the bloods are drawn so a later change is interpretable.
• Escalate for imaging where transaminases are rising and platelets falling together, rather than waiting for a seizure.
• Remember that magnesium sulphate remains the treatment for eclampsia regardless of whether PRES is confirmed.

Why it matters

It moves PRES from a radiological afterthought to something the routine pre-eclampsia bloods can point you towards.

Don't overread it

These are pooled observational associations — deranged liver enzymes do not diagnose PRES, and normal ones do not exclude it.

The statistics, in plain English

An I² of 98.5% means almost all the variation between studies is real disagreement rather than chance, so the pooled incidence of 38.68% should not be read as a probability for any individual woman — the studies were counting different populations under different imaging thresholds. The laboratory differences are more trustworthy because they point the same way across studies, though they are mean differences between groups and not a diagnostic threshold. The raised maternal mortality risk (RR 4.06) did not reach statistical significance, so it should be treated as a hypothesis rather than a finding.

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