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A 27-year-old woman was referred at 37 weeks’ gestation for confirmation of malpresentation. Incidental hydrocephalus was found on ultrasound. Fetal MRI confirmed dilation of the lateral and third ventricles and an extensive mixed signal intensity cystic structure in the left hemisphere (7×6×4 cm) with evidence of blood products and restricted diffusion (figure 1A). The maternal platelet count was 114×109/L, and maternal antibody testing for neonatal alloimmune thrombocytopaenia (NAIT) was positive (anti-HPA (human platelet-specific antigen) 1a alloantibodies, maternal genotype HPA 1bb, paternal genotype HPA 1ab).
Subsequently a live female infant was delivered by caesarean section. At birth the infant had widened sutures and a petechial rash. The platelet count was 4×109/L and the infant received two HPA1a-negative platelet transfusions shortly after birth. MRI the next day confirmed posthaemorrhagic ventricular dilation and a large haemorrhagic parenchymal infarction with porencephalic cyst (figure 1B, arrow). She required a cystoventriculoperitoneal shunt at 4 weeks.
NAIT is an IgG mediated disorder that occurs after maternal exposure to incompatible fetal paternally derived platelet antigens; it can occur in first pregnancies.1 Outcomes for NAIT with intracranial haemorrhage (ICH) are poor: registry data suggest that only 12% of children with ICH secondary to NAIT survive without significant neurodisability.2 Detailed antenatal imaging and testing for NAIT when fetal intracranial haemorrhage is suspected enables planned early treatment with matched platelets if the diagnosis is confirmed, which minimises the duration of postnatal profound thrombocytopenia and risk of further haemorrhage.
Contributors TW devised idea for article, selected appropriate images and drafted the text. GW selected appropriate images for article and contributed to text. JK revised the text for important intellectual content. SC revised the text for important intellectual content. JPB devised idea for article, selected appropriate images and drafted the text. All authors approved the final submitted version.
Competing interests None.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.
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