Fetal/neonatal allo-immune thrombocytopenia (FNAIT): past, present, and future

We reviewed the English, American, and German literature for articles describing the prevalence, clinical presentation, outcome, therapeutic options, and screening possibilities for fetal/neonatal allo-immune thrombocytopenia (FNAIT), published between January 1950 and March 2007. The reported prevalence of FNAIT in human platelet antigen (HPA)-1a-negative women varies between 1/600 to 1/5000 live births among various populations. The typical picture is that of a neonate presenting with purpura minutes to hours after birth, born to a healthy mother with no history of infection or abnormal bleeding, after an uneventful pregnancy with a normal maternal platelet count. Thrombocytopenia in FNAIT can be severe, with intracranial hemorrhage occurring in 10% to 30% of severe FNAIT cases. Several types of neonatal treatment have been proposed, of which transfusion of HPA-compatible platelets is most effective. Antenatal management of FNAIT consists of weekly maternal intravenous immunoglobulin (IVIG) infusions, with or without oral steroid therapy. Serial fetal platelet transfusions can be provided in cases of failure of IVIG therapy, but the multiple cordocenteses that would be required to administer the platelets entail substantial risk. The possibilities for antenatal screening of first pregnancies are limited. Postnatal screening does not prevent neonatal morbidity and mortality.

Obstetricians & Gynecologists, Family Physicians.

After completion of this article, the reader should be able to summarize the many and varied causes of neonatal thrombocytopenia, explain that fetal/neonatal allo-immune thrombocytopenia (FNAIT) is a rare but devastating cause with potential high risk of recurrence, and recall the treatment options for FNAIT as well as their potential side effects.