Usual cause
Alloimmunisation to platelet-specific antigens, most often Human Platelet Antigen 1a (HPA-1a).
Incidence
Rare.
Main clinical features
Development of dramatic, sudden and self-limiting thrombocytopenia, typically 7-10 days after a blood transfusion in a patient with a history of sensitisation by either pregnancy or transfusion. While the immune specificity may be to a platelet-specific antigen the patient lacks, both autologous and allogeneic platelets are destroyed.
Investigation
Demonstrate anti-platelet antibody.
Intervention
Intravenous immunoglobulin. Antigen-negative platelets may be indicated if platelet transfusion is required but this is controversial. Inform ARCBS.