The utility of the PFA-100 in the identification of von Willebrand disease: a concise review

The PFA-100 (platelet function analyser; Dade-Behring, Marburg, Germany) is a relatively new tool for the investigation of primary hemostasis. Recent studies have shown its utility as a screening tool for investigating various platelet disorders and possible von Willebrand disorder (vWD), both in the initial investigation and in subsequent therapeutic monitoring of desmopressin therapy. This article reviews current findings with respect to the identification of vWD, and highlights both the benefits and the limitations of its clinical utility. In brief, sensitivity to vWD types 2A, 2B, 2M, and 3 is > 98%, but overall sensitivity to vWD (types 1, 2A, 2B, 2M, and 3 combined) is ~85 to 90%. Ultimately, the high sensitivity of the PFA-100 to vWD and its simplicity of use provide its greatest strengths. However, because it is a global test system, and also sensitive to low hematocrit, low platelet counts, and platelet dysfunction (both congenital and acquired; e.g., secondary to medication such as aspirin) it must be recognized that the PFA-100 is neither specific for, nor predictive of, any particular disorder (inclusive of vWD). Nevertheless, used appropriately, the PFA-100 can be considered a worthwhile addition to the hemostasis laboratory involved in the diagnosis or therapeutic monitoring of vWD, and a normal PFA-100 result can be used with some confidence to exclude severe vWD.