RESUMO
Von Willebrand disease (vWD) is a frequent congenital bleeding disorder with an autosomal, usually dominant, mode of inheritance. Its clinical expression and mechanism (quantitative or qualitative abnormality of von Willebrand Factor) are extremely heterogeneous. The bleeding symptoms vary in intensity from one patient to the other (including in the same family) and also with time in a given patient. The role of vWF in platelet adhesion to the subendothelium and as a carrier of Factor VIII explains the prolongation of the bleeding time and of the APTT in the typical forms of vWD. These tests, however, may be only slightly abnormal or even normal in the numerous mild forms of the disease which are often diagnosed because of bleeding complications following surgery or delivery. The specific tests (assay of vWF antigen, assay of ristocetin-cofactor activity, assay of Factor VIII activity) usually lead to the diagnosis. The latter remains uncertain, however, in some cases where results are at the lower limit of normal. Once the diagnosis is established, highly specialized methods are required to determine the type of vWD. The therapy of vWD relies on the use of either virus inactivated plasma concentrates or DDAVP.
