Antenatal treatment of alloimmune thrombocytopenia.

OBJECTIVE: Neonatal alloimmune thrombocytopenia is caused by platelet antigen incompatibility between the mother and fetus. Affected fetuses may have severe thrombocytopenia leading to intracranial hemorrhage before or at birth. We sought to treat this condition in utero to prevent these hemorrhages.

METHODS: Eighteen women who had previously delivered infants with severe alloimmune thrombocytopenia were treated with weekly infusions of intravenous gamma globulin from the diagnosis of fetal thrombocytopenia until birth; nine were also treated with corticosteroids.

RESULTS: There were no intracranial hemorrhages in the treated fetuses, compared with ten cases among the 21 untreated siblings (48%). Only three treated fetuses, compared with 16 of 20 untreated siblings, had platelet counts of less than 30,000/microL, with no bleeding complications.

CONCLUSION: Antenatal treatment of alloimmune thrombocytopenia with weekly gamma globulin effectively improves the fetal platelet count and prevents intracranial hemorrhage.