Isoimmune Neonatal Thrombocytopenic Purpura : Clinical and Therapeutic Considerations

1. Serologic tests utilizing complement fixation have allowed differentiation of isoimmune neonatal thrombocytopenia from other forms of congenital thrombocytopenia.

2. The pathogenesis of the isoimmune disease involves fetal-maternal incompatibility of platelet antigens, and destruction of fetal platelets by a transplacental transfer of maternal antibody.

3. Three different platelet antigens have been implicated in neonatal purpura. None of these antigens correspond to known erythrocyte antigens, but two of the platelet antigens are shared by granulocytes and lymphocytes.

4. Review of the literature of probable isoimmune neonatal purpura and our own cases reveals that in untreated cases death occurs in approximately 12 per cent of cases, and platelet counts usually do not remain below 60,000/ mm.³ longer than 21 days.

5. In two of three instances in which neonatal thrombocytopenia was anticipated as a result of serologic tests done on the mothers, antepartum steroids may have benefited the infant.

6. Steroid therapy to the infant appears to shorten the duration of thrombocytopenia, and in one instance exchange transfusion led to immediate cessation of hemorrhage and rapid return of platelets to normal.