Isoimmune neonatal thrombocytopenic purpura.

Ten cases of isoimmune neonatal thrombocytopenic purpura (4 pairs of siblings and 2 singletons) are described. The condition was diagnosed by excluding other causes of thrombocytopenia , and in 8 cases it was confirmed by detecting antiplatelet antibodies in the mother. Perhaps steroids should be given to affected infants as soon as the condition is diagnosed in order to stabilise the capillary membrane. Exchange transfusion, using platelet antigen-negative blood if available, helps to remove antibodies and should be followed by the infusion of antigen-negative platelets, easily obtained from the mother by platelet-phoresis. The use of random donor platelets (as in 3 of these cases) was ineffective because 98% of the population are platelet antigen-positive. Nine of the infants recovered completely. The exception was an infant who developed hydrocephalus, possibly as a result of intracranial haemorrhage.