Antenatal diagnosis and management of fetomaternal alloimmune thrombocytopenia.

Fetomaternal alloimmune thrombocytopenia (FMAT) arises from maternal-fetal platelet antigen incompatibility, which stimulates the production of maternal immunoglobulin G (IgG) platelet-specific antibody. Transplacental passage of this antibody results in fetal platelet destruction and consequent thrombocytopenia. Sequelae of thrombocytopenia may be observed in both the fetus and neonate with intracranial hemorrhage occurring in approximately 10 to 30% of affected infants. No antenatal universal screening test is currently available to detect the 50% of cases occurring in the first pregnancy. The recurrence rate in subsequent pregnancies is 75 to 85%, with a tendency to increasing disease severity. Paternal platelet genotyping is recommended to assist in risk counseling following an affected pregnancy. Prenatal therapeutic strategies are aimed at elevating the fetal platelet count in affected pregnancies and thus decreasing hemorrhagic sequelae. The most effective treatment regimen is uncertain, but encouraging results are reported with the use of maternal intravenous gamma globulin. We report our experience in the antenatal diagnosis and management of FMAT.