A device for preventing air escape and maintaining colonic air distension can include a body, a distal gasket coupled to a distal end of the body, a proximal gasket coupled to a proximal end of the body, and a diaphragm coupled to the proximal gasket. The distal and proximal gaskets can form a fluid-tight seal with a colonoscope positioned within central bores of the distal gasket, the body, and the proximal gasket, and the diaphragm can conform to and form a fluid-tight seal with at least one of an anus and a stoma of a subject.
