A container (1) for carrying out medical or veterinary procedures, comprising: a reservoir (2) having a closed end (2a) and an open end (2b)； a stopper (3) at least partially inserted sealingly in the reservoir (2) at the open end (2b) to maintain a pre-established initial pressure value of a gaseous fluid present inside the reservoir (2). The stopper (3) delimits an initial volume inside the reservoir (2) and is shaped in such a manner that a conduit can pass through it so as to enable the reservoir (2) to be filled with a liquid biological sample. The container (1) comprises a movement member (4) that is associated with the reservoir (2) and operatively active on the stopper (3) so as to move the latter between at least a first operative position, in which it delimits the initial volume, and at least a second stable operative position, in which the stopper (3) delimits a final volume that is larger or smaller than the initial volume so as to decrease or increase the pressure value of the gaseous fluid present inside the reservoir (2), respectively.
