Role of Viscoelastometric Testing in the Development and Validation of a Clinical-biological Score for Predicting Bleeding in Patients With Malignant Haematological Disorders and Severe Thrombocytopenia

Inclusion Criteria: * Adult patients; * Who have been informed about the study and have freely given their informed consent to participate in the study; * With a malignant haematological disorder or bone marrow failure, whether treated or untreated and at any stage of treatment; * With central thrombocytopenia strictly below 20 G/L in a blood sample taken less than 72 hours ago and not having received a transfusion since; * Admitted to a haematology day unit or inpatient ward, or being followed up at a haematology outpatient clinic; * With or without active bleeding; * Affiliated with or covered by a social security scheme. Exclusion Criteria: * Patients who have received at least one of the following treatments: * Antiplatelet agents within 7 days prior to enrolment, * Vitamin K antagonists within 7 days prior to enrolment, * Direct oral anticoagulants within 72 hours prior to enrolment, * Low molecular weight heparin within 24 hours prior to inclusion, * Unfractionated heparin within 6 hours prior to inclusion, * Bruton's tyrosine kinase inhibitor (ibrutinib, zanubrutinib or acalabrutinib) within 72 hours prior to inclusion; * Patients with a history of thrombopathy; * Patients with a history of haemostatic disorders carrying a risk of haemorrhage or thrombosis; * Thrombocytopenia associated with immune thrombocytopenic purpura or disseminated intravascular coagulation; * Patients already enrolled in the study; * Pregnant or breastfeeding women; * Patients under guardianship or curatorship; * Patients who do not understand French; * Patients under judicial protection.