Abstract: A device and its method of operation for assisting in the advancement of an endoscope through the colon or other body passage. The device includes a sleeve having an annular chamber defined in part by an outer wall of elastomeric material. A multiplicity of resilient hollow protrusions are formed in the wall and expand outwardly and rearwardly when the chamber is filled with a suitable fluid under pressure and which retract inwardly and forwardly when the pressure of the fluid is reduced. The device extends about and is secured to the distal end portion of an endoscope and, upon repetitious expansion and retraction of the protrusions by reason of pulsing pressure fluctuations within the chamber, such device helps to advance the scope along a body passage.