Alloimmune thrombocytopenia of the fetus and the newborn.

Fetal/neonatal alloimmune thrombocytopenia results from a maternal alloimmunization against fetal platelet antigens. Care must be taken in making a correct diagnosis that eliminates other causes of thrombocytopenia that may occur during pregnancy. Biological diagnosis is normally made by platelet genotyping and search for the maternal alloantibody using monoclonal antibodies in an antigen capture assay. Fetal alloimmune thrombocytopenia, when severe, may result in intracerebral hemorrhage leading to hydrocephalus and death of the fetus. Neonatal alloimmune thrombocytopenia may be present in an otherwise healthy infant. While screening procedures are not in place to detect fetal/neonatal alloimmune thrombocytopenia, it is true that fetal hydrocephalus, unexplained fetal thrombocytopenia with or without anemia, or recurrent miscarriages should be adequate indicators for suspecting fetomaternal alloimmune thrombocytopenia. Multiparous women with a history of giving birth to at least one alloimmune thrombocytopenic infant should be carefully monitored in subsequent pregnancies. Postnatal management of neonatal alloimmune thrombocytopenia involves compatible platelet transfusion in the neonate. Antenatal management of fetal alloimmune thrombocytopenia is controversial and includes a combination of maternal intravenous gamma globulin (i.v.IgG) administration, intrauterine platelet transfusions, and corticosteroid therapy, while monitoring fetal platelet counts closely throughout the course of pregnancy. Screening of pregnant women may become a public health issue only after antenatal therapy is more standardized.