The invention relates to a device (200) for taking a sample of a body fluid, such as blood, to be incorporated into a fluid circuit of a perfusion (100) of a patient who has a perfusion catheter (104), said device having a tubular structure (202) for connecting to the fluid circuit of the perfusion, provided with a zone for intubation, during use, of a sampling channel (300) comprising a distal end (301) and a means (203) for holding, during use, in the tubular structure, the part of the sampling channel (300) comprising a distal end (301) in such a way that the distal end (301) is oriented towards the perfusion catheter (104), in the direction of flow (F1) of the perfusion product (102), from a perfusion product reservoir (101) towards the perfusion catheter (104).
