Bleeding of Unknown Cause: a Swiss Case-control Study

Inclusion Criteria: * Man with ISTH BAT\>3. If the calculated score includes a surgical bleeding, then two other items of the score should be \>0 * Woman with ISTH BAT \>5 points. If the calculated score includes a surgical or a postpartum bleeding, then two other items of the score should be \>0 Exclusion Criteria: * Ongoing pregnancy * Intake of antithrombotic treatment or non-steroidal anti-inflammatory drugs for least 10 days at time of blood collection * Intake of antifibrinolytic or blood product administration (factor concentrate, frozen fresh plasma, prothrombin complex concentrate) for least 14 days before blood collection * Active cancer (defined as cancer diagnosis within the last five years or treatment within the two last years before study inclusion) * Active autoimmune disease * Active chronic inflammatory disease * Severe liver disease (cirrhosis \> Child A) * Renal insufficiency stage 3 * Active or recent infection (within the last 30 days) * Recent hospitalization (\<3 months) * Recent surgery (\<3 months) * Recent trauma requiring medical intervention (\<3 months)