Abstract: A resectoscope used in performing transurethral operations has a telescope extending longitudinally of the instrument which is supported and stabilized by an elongated metallic tube which at its proximate end is fixed to the block of the instrument. In accordance with the invention the distal end of the tube is extended beyond the distal end of the telescope sufficiently that there will be no interference with illumination through the telescope but electrical arcing between the bare wire of the cutting loop of the instrument and the telescope will be prevented. The tube extension may be made of metal or of a material which is electrically nonconductive.