An arrangement in connection with the handling of patient fluids, comprising asuction canister (320) open at one end, a cover (310) for closing the suctioncanister (320), a suction bag (300) fastened to the cover (310), and anunderpressure apparatus (340) for applying underpressure to a space betweenthe suction canister (320) and the suction bag (300). The arrangement furthercomprises fastening means (330, 332) for keeping the suction bag (300)narrowed in such a manner that the width and length of the suction bag (300)are at least along part of the suction bag (300) smaller than when the suctionbag (300) is opened, and the fastening means (330, 332) are arranged torelease the suction bag (300) to be opened into the suction canister (320)under the action of the underpressure when the cover (310) is closed.
