Intravenous immunoglobulin g therapy in fetal and neonatal alloimmune thrombocytopenia.

Neonatal alloimmune thrombocytopenia (NAIT) is a rare disorder in the neonatal period, occurring in 1 in 2000 to 5000 births. The clinical syndrome of NAIT can be varied, but the resulting thrombocytopenia can be very severe and can result in serious haemorrhage in the fetus and neonate. At least 5 human platelet antigen systems have been described, and all have been implicated in cases of NAIT. Approximately 50% of platelet antigen-incompatible firstborn infants will be affected. The risk of recurrence in subsequent pregnancies is high, estimated at >75%, with the disease being either equally or more severe than in the first infant. Mortality in NAIT is estimated to be 10%, and is usually associated with intracranial haemorrhage. The incidence of intracranial haemorrhage is estimated to be approximately 14%, with approximately 25% occurring antenatally. In an effort to prevent these severe complications, therapy is usually instituted in infants with severe thrombocytopenia from NAIT. Treatment strategies have included appropriate, compatible platelet transfusion, corticosteroid use and exchange transfusion. However, success in treating immune-mediated thrombocytopenia with intravenous immunoglobulins (IVIg) has prompted the use of this therapy in fetuses and infants with NAIT. IVIg has demonstrated efficacy in both of these clinical situations. The literature concerning the use of IVIg, both ante- and post-natally, is reviewed, and treatment strategies for infants and fetuses affected by NAIT are discussed.