Fetal alloimmune thrombocytopenia: is less invasive antenatal management safe?

The aim of this study was to review recent multicenter data on antenatal management of anti-HPA-1a fetal alloimmune thrombocytopenia and, based on this retrospective study and on recent literature, to evaluate if FBS modified the obstetrical management.

This retrospective study in France includes 23 pregnancies in 21 women who had a previous thrombocytopenic infant due to anti HPA-1a alloimmunization. All pregnant women received intravenous immunoglobulin (IVIG) treatment, with or without corticosteroids. Fetal blood sampling (FBS) was performed before any therapy (four cases) or during pregnancy (nine cases).

Infants whose mother received treatment had a significantly higher neonatal platelet count than the corresponding sibling (p = 0.003). In eight cases, therapy was started late during pregnancy. In three cases, treatment was discontinued 3 or 4 weeks before birth, and this was associated with a poorer result. No in utero intracranial hemorrhage was recorded in the infants for whom maternal therapy continued to term. Adverse effects were not observed in any case. All babies were delivered by cesarean even when FBS was performed. One emergency cesarean was performed for fetal bradycardia after FBS.

This study confirmed that maternal therapy with intravenous immunoglobulin for fetal alloimmune thrombocytopenia gives satisfactory results. It also showed that a less invasive approach, especially a reduction in the number of fetal blood samples, is possible without deleterious consequences. This observation suggests also to start IVIG early during pregnancy and to continue treatment up to delivery.