Abstract: A flushing device (8) usable in the catheterization of a bladder includes a flexible container (9) defining a compartment (12) adapted to be filled with a liquid, and a connector (10) attached to the container (9). The connector (10) is adapted to be connected to a catheter, and the connector (10) is provided with an opening (11). The flexible container (9) is interconnected with the connector (10) via a lumen (13), such that liquid is allowed to pass through the connector (10) in the lumen (13) from the flexible container (9) and exit through the opening (11). The flexible container further includes a non-return valve (14) arranged in the lumen (13). A kit including such flushing device (8) is also described.