Abstract: A method and apparatus and an adapter device for testing the integrity of a dressing applied to a wound for the purpose of applying topical negative pressure therapy to that wound are described, the method comprising the steps of: applying a dressing to the wound so as to create a sealed cavity over the wound, the cavity having an aspiration conduit operably connected thereto for the purpose of creating a vacuum in the cavity; providing adapter device means to a liquid scalpel so as to create a substantially closed volume around a region in which a water jet exists in operation of the water scalpel; connecting a free end of the aspiration conduit to the closed volume formed by the adapter device means on the scalpel; and, using a vacuum created by a venturi effect of the liquid jet in the closed volume to create a vacuum in the dressing cavity.