[Post-transfusion purpura: and cause of severe postoperative thrombopenia]

A 59-year-old woman developed an acute and severe thrombocytopenia (platelet count below 10.10(9).L-1) with active bleeding, 6 days after a massive transfusion for intraoperative haemorrhagic shock. The diagnosis of post-transfusion purpura (PTP) was confirmed by the presence of an allo-antibody directed against HPA-1a platelet antigen. The patient and her daughter had a rare HPA-1b platelet phenotype, but also belonged to the HLA DR3 phenotype, frequently associated with PTP. This case shows the therapeutic difficulties of postoperative PTP. Despite active bleeding, this syndrome requires the discontinuation of transfusions of incompatible platelets. Transfusion of phenotyped platelets is often inefficient. Red cell concentrates must be platelet and plasma free. Immunomodulating therapy can shorten the time course. Preventive measures, particularly autologous transfusions, are necessary for subsequent haemorrhagic surgery or parturition.