This invention relates generally to an endoscope accessory. This device uses an overtube with an inflatable positioning balloon that can be inflated after placement of the overtube just proximal to the tip of the endoscope or echoendoscope. This balloon creates a temporary blockade of the gastrointestinal tract proximal to the portion that needs to be examined. The other part of the device is a catheter with an occlusion balloon affixed to its free endportion and can be passed through a passageway within the overtube and extended beyond the tip of the endoscope, distal to the part of the gastrointestinal tract that needs to be examined. Inflation of this balloon together with positioning balloon creates a closed space within the body cavity that can be filled with air or water for improving the quality of the examination with regular endoscope of echoendoscope, respectively, while reducing the examination complications.