The invention relates to a method for operating a preparation device (10) for preparing surgical instruments (20), in particular endoscopes (20). In order to carry out the method, among others, at least one or more channels of a surgical instrument (20) are supplied with a medium, in particular a flushing or cleaning medium, in at least one preparation step, the channel(s) of the surgical instrument (20) being connected to an adapter (18), wherein the adapter (18) is connected to an adapter connection element (22), which is provided in a flushing chamber (12), for the adapter in order to carry out the at least one preparation step. The at least one or more preparation step(s) are carried out in a preparation device (10) flushing chamber (12) which is provided with a door (16) and is closed by means of the door. The open flushing chamber (12) is closed in a closing process by means of the closing movement of the door (16) prior to carrying out at least one preparation step for the surgical instrument (20) arranged in the flushing chamber (12). A coupling device for the adapter (18) and the adapter connection element (22) are actuated by the closing process for closing the flushing chamber (12), and the coupling device is designed such that the adapter (18) and the adapter connection element (22) are connected together after the closing process. The invention further relates to a preparation device (10) for preparing surgical instruments (20), in particular endoscopes (20), comprising a flushing chamber (12) for receiving an instrument (20).
