ABSTRACT
Fetal/Neonatal alloimmune thrombocytopenia [FNAIT], resulting from maternal alloimmunisation against fetal platelet antigens, is a serious affection. The frequency has been estimated to be 1 out of 800-1000 live births. We report a new observation of alloimmune neonatal thrombocytopeni due to anti HPA-5b [Bra] antibodies. Case report: A male full term neonate presented at birth with a thrombocytopenia unexplained by usual causes of neonatal thrombocytopenia. Alloimmune neonatal thrombocytopenia was diagnosed by the determination of platelets and neonatal patelets antigens phenotypes HPA-5b [antiBra] antibodies in maternal sera, absent at delivery, were identified four months neonatal later. A favourable evolution was obtained after maternal washed platelet transfusion. Alloimmune thrombocytopenia is a seious affection, which exposs to intracranial haemorrhage. Difficulties in detemining the diagnosis should not delay therapy, depending on exclusion of other causes