laboratory diagnostic - coagulation - Factor Von Willebrand (Ristocetin Cofactor), ADAMTS-13 factor protease activity, serum or citrated plasma 2x2ml. The plasma or serum must be frozen within 1 hour after collection and must be sent in the frozen samples container. Attach the clinical data relating to the patient (major inflammatory syndrome, pregnancy, etc.), the circumstances (bleeding, thrombosis, preoperative evaluation, etc.) and the genealogical tree. If ADAMTS-13 factor protease activity is low, antibodies screening is performed, Chronometric, ssso, todylaboratories®, bmn, code L16LD1560