Fetal and neonatal alloimmune thrombocytopenia - pathogenesis, diagnosis and therapy

Abstract

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) represents the most frequent cause of severe fetal or neonatal severe thrombocytopenia and intracranial haemorrhage in full-term infants. It should be suspected with isolated thrombocytopenia or with a personal or family history of alloimmune thrombocytopenia, especially if the fetus experienced intracranial haemorrhage. FNAIT results from maternal alloimmunization during pregnancy against specific fetal platelet antigens (HPA) inherited from the father and absent in the mother. These maternal IgG alloantibodies bind to the fetal platelets, leadind to their distruction. Although rare, FNAIT has a poor outcome, due to possible severe complications and long-term disabilities. The immediate antenatal maternal treatment, using high dose i.v. IG and corticosteroids has shown that both the degree of thrombocytopenia in the fetus and the risk of intracranial haemorrhage can be reduced. The aim of this paper is to put an exclamation point on the importance of adequate diagnosis and treatment on reducing both associated morbidity and mortality. We worked on a meta-analysis of numerous studies, drawing conclusions on pathogenesis, genetic testing, diagnosis and screening principles, as well as on treatment recommendations based on antenatal risk stratification algorithms. We present in detail the severity-based approach for treatment of pregnancies at undetermined risk, standard, high and extremely high risk, so this paper could be even used as a guide to FNAIT management. An important chapter is the management of subsequent pregnancies, where we presented the latest protocols of recommendation for parental and fetal genotyping and methods for estimating the severity of FNAIT.