A medical device sheath apparatus including: a fitting being suitable for receiving the medical device in a self sealing manner; a first sheath for receiving the medical device as it passes through the fitting; a second sheath surrounding the first sheath; a dilator defining a treatment area, coupled to at least the second sheath, and being suitable for dilating a bodily cavity and passing therapeutic or diagnostic energy in such forms as electromagnetic radiation or acoustic energy there through; and, a window operatively positioned with respect to the first sheath so as to enable viewing of an area substantially adjacent the second sheath upon insertion of the medical device into the apparatus.