Cystoscope is a medical instrument used for examining the bladder and urethra. It consists of a long, narrow tube with a light source and a lens system for magnifying the view of the interior of the bladder. The cystoscope is inserted through the urethra, the tube that carries urine from the bladder to the outside of the body, and into the bladder, allowing the doctor to inspect the inside of the bladder for signs of disease or other conditions.