Between 10 and 15% of critically ill patients require platelet transfusion within their intensive care unit (ICU).

Platelets (PLT) are given to prevent bleeding in thrombocytopenic patients or to treat bleeding as part of massive transfusion or in bleeding thrombocytopenic patients.

International and local guidelines (American Association of Blood Banks-AABB) are mainly based on experts' opinion. The efficacy of PLT transfusion in the ICU setting remains poorly studied and unknown and the administration of PLT may be associated with adverse effects including an increased risk of hospital acquired infection. Finally, the short PLT shelve-life may be responsible for inventory issues. Altogether, this makes very important to improve the evidence that support PLT transfusion in ICU patients.

This is a multicentre prospective observational study that aims to first determine PLT transfusion efficacy and to identify the parameters associated with transfusion efficacy and to analyse the compliance with international (and local) guidelines of PLT transfusion in ICU patients.

Inclusion Criteria:

• Patients admitted to intensive care and receiving at least one platelet transfusion in intensive care unit

Exclusion Criteria:

• Age less than 18

Patients admitted to intensive care and receiving platelet transfusion whatever the reason for it.

All collected data that underlie results in a publication

Data will be available after the publication of result and ending three years maximum following the last visit of the last patient

Data access requests will be reviewed by the internal committee of Brest UH. requestors will be required to sign and complete a data access agreement