Evaluating the child with purpura.

Purpura is the result of hemorrhage into the skin or mucosal membrane. It may represent a relatively benign condition or herald the presence of a serious underlying disorder. Purpura may be secondary to thrombocytopenia, platelet dysfunction, coagulation factor deficiency or vascular defect. Investigation to confirm a diagnosis or to seek reassurance is important. Frequently, the diagnosis can be established on the basis of a careful history and physical examination, and a few key laboratory tests. Indicated tests include a complete blood cell count with platelet count, a peripheral blood smear, and prothrombin and activated partial thromboplastin times.