This invention relates generally to a diagnostic and therapeutic device. According to some aspects of the invention, the device may be composed of a flexible sheet that is wrapped around the endoscope shaft to form a flexible overtube. The overtube may include an inflatable positioning ring that may be inflated after placement of the overtube just proximal to the tip of the endoscope or colonoscope to secure the position of the overtube and create a seal within the body cavity. The overtube also may include an inflatable sealing band within the internal surface of the overtube that when inflated secure the position of the endoscope within the overtube and create a seal around the endoscope shaft. According to other aspects of the invention, the device may have a catheter with an occlusion balloon at its free end portion that is carried by the overtube and extends beyond the dostal endportion of the overtube and the tip of the endoscope that when inflated secure its position within the body cavity and create a seal within the body cavity. Inflation of the positioning ring, sealing band and occlusion balloon defines an examination compartment within the body cavity at the tip of the endoscope. The examination compartment may be filled with air, or with water, depending on applications. In addition the examination compartment can be thoroughly lavaged using the irrigation tube system.
