A therapy system for treating a tissue site with negative-pressure therapy and/or fluid instillation therapy in response to information received from a diagnostic module is described. The therapy system may include a dressing, a negative-pressure source, a container, and a diagnostic module. The dressing be placed on the tissue site, and the negative-pressure source may be fluidly coupled to the dressing. The container may be fluidly coupled to the dressing and to the negative-pressure source to receive fluid from the tissue site. The diagnostic module may be exposed to gas associated with the fluid from the tissue site. The diagnostic module may comprise a sensor configured to detect a condition of the tissue site and to generate an output based on the detected condition. The sensor may be configured to detect a volatile organic compound. The diagnostic module may be positioned on the container.