Abstract: A cavity (3) such as the urethra of a patient is lined by providing a lining device that comprises an eversible chamber (12) and a liner (16) connected thereto. Fluid pressure is applied to the chamber (12) to cause the chamber (12) to evert and advance into the cavity (3) such that the chamber (12) carries the liner (16) into the cavity. A vacuum is then applied to the chamber (12) to cause it to deflate. A part, such as a catheter or cable, can then be inserted into the cavity through the liner (16). If the cavity is the urethra of a patient, the liner shields the catheter from the distal part (1) of the urethra which is colonised with bacteria, and therefore reduces the risk of a urinary tract infection.

Abstract: Apparatus for inserting an instrument (1) in a flexible body cavity is disclosed. The apparatus includes a sheath (3) having an inner chamber (31) for accommodating the instrument (1) and an outer chamber (41) surrounding the inner chamber, thereby defining an enclosed space between the inner chamber and the outer chamber Fluid pressure is temporarily applied to thse enclosed space so as to expand the outer chamber to facilitate insertion of the instrument in the body cavity. In another embodiment the inner chamber is expandable to have a diameter equal to or greater than the diameter of the outer chamber, and wherein the outer chamber incorporates one or more lines of weakness for facilitating release and expansion of the inner chamber and withdrawal of the instrument from the inner chamber. In yet another embodiment the sheath includes at its distal end a convex lens for use by a camera in obtaining images of said body cavity.