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.