Cystoscopy allows the doctor to look inside your bladder during an operation. A chemical called hexyl amino levulinate (HAL) will be inserted into your bladder. This is done by passing a fine tube (catheter) along your urethra and into the bladder. With a special camera and a blue light, your doctor can then check your bladder. During the operation, cancer cells absorb the chemical and then glow red in the blue light, so they are easier to see.