The invention relates to a method of treating haemorrhagic fluid in a patient during a surgical procedure, for the purpose of autotransfusion, comprising: a haemorrhagic fluid recovery step involving the simultaneous introduction of agents such as anticoagulants and/or diluents； and at least one step involving the mechanical separation/concentration of the haemodiluted haemorrhagic fluid in order to concentrate said fluid in red blood cells and to partially purify same, said phase being collected in a sterile manner so that it can be autotransfused to the patient. The invention also relates to the associated device.
