From concept to practice: Screening for fetal and neonatal alloimmune thrombocytopenia (FNAIT)

Abstract

Affecting 1 per 1000 to 2000 pregnancies, Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT) is the leading cause for (severe) thrombocytopenia in term neonates. Due to an incompatibility between fetal and maternal platelets, maternal alloantibodies are formed against paternally derived human platelet antigens (HPAs). The alloantibodies can cross the placenta into the fetal circulation, where they can destruct the fetal platelets. As a result, severe thrombocytopenia may occur, potentially leading to intracranial hemorrhage (ICH) or severe organ bleeding during pregnancy or shortly after birth. In the absence of a universal prenatal screening program focussed on HPA-1a, FNAIT is often diagnosed too late, typically after the onset of severe fetal or neonatal bleeding complications. A screening program could be very effective in identifying the first pregnancy complicated with FNAIT, allowing timely intervention and prevent severe ICH and its associated long-term permanent sequelae. The aim of this review is to provide a comprehensive overview of the existing evidence regarding a possible future screening program for FNAIT. Additionally, challenges will be explored that need to be addressed for successful implementation of a screening program.