The invention relates to a system, and an associated method for using the system, for treating hemorrhagic fluid previously taken from a patient for the purpose of autotransfusion, including a unit for treating (100) hemorrhagic fluid, said treatment unit (100) comprising: - a filtration device (110) for tangential filtration comprising a filtration membrane (113) arranged in a housing (114) so as to separate an intake chamber (111) from a discharge chamber (112), the inlet chamber (111) and the discharge chamber (112) each having an inlet (111a； 112a) and an outlet (111b； 112b) for fluids； - a treatment pouch (140) having an inlet (140a) and an outlet (140b) fluidly connected by a recirculation line (150) at the outlet (111b) and at the inlet (111a) of the inlet chamber (111) of the filtration device (110), respectively, allowing hemorrhagic fluid to circulate in the recirculation line (150) in a direction running from the outlet (140b) of the treatment pouch (40) toward the inlet (140a) of the treatment pouch (140) through the inlet chamber (111) of the filtration device (110)； - a cleaning line (180) fluidly connected to the inlet (112a) of the discharge chamber (112) of the filtration device (110) to convey cleaning liquid into said discharge chamber (112)； and - a first flow regulation member (181) arranged to regulate the flow in the cleaning line (180) and a second flow regulation member (131) arranged to regulate the flow in a discharge line (130) fluidly connected to the outlet (112b) of the discharge chamber (112) of the filtration device (110), so as to be able to control the pressure of cleaning liquid in the discharge chamber (112).L'invention porte sur un système de traitement, et son procédé d'utilisation associé,d'un liquide hémorragique préalablement prélevé un patient en vue d'une autotransfusion, incluant une unité de traitement (100) du liquide hémorragique, ladite unité de traitement (100) comprenant: - un dispositif de filtration (110) pour fil
