a system and method for detecting perforations in a body cavity . in accordance with the method of the invention , a fluid is delivered into a body cavity to slightly pressurize the cavity . a pressure sensing system monitors the pressure within the cavity for a predetermined test period . if cavity pressure is not substantially sustained during the test period , the physician is alerted to further assess the cavity for perforations before initiating treatment within the cavity . in a preferred form of the system , a medical treatment system such as an rf ablation system is provided with perforation detection functionality . the system preferably includes a pre - test and post - test lockout system . the lockout system prevents rf power delivery unless , during a predetermined test period , the pressure sensing system determines that no perforation exists , or unless a previously performed perforation detection procedure determined a perforation was present but the lockout system was subsequently overridden by the physician .