The bleeding child. Part I: primary hemostatic disorders.

Mucocutaneous bleeding is common in childhood and may be the result of primary hemostatic disorders such as vascular abnormalities, von Willebrand disease, thrombocytopenia, and platelet dysfunction. A detailed bleeding history and physical examination are essential to distinguish between normal and abnormal bleeding and to decide whether it is necessary to perform further laboratory evaluation. Initial laboratory tests include complete blood count, peripheral blood smear, mean platelet volume, von Willebrand factor (VWF) antigen assay, VWF ristocetin cofactor activity, and factor VIII activity. Once thrombocytopenia and von Willebrand disease have been excluded, platelet function should be tested by platelet aggregation. Additional specific diagnostic tests, such as platelet secretion tests and flow cytometry for the detection of platelet surface glycoprotein expression, are needed to confirm the raised hypothesis.