Also referred to as VCUG or voiding cystogram. A specific X-ray that examines the urinary tract. A catheter (hollows tube) is placed in the urethra (tube that drains urine from the bladder to the outside of the body)and the bladder is filled with a liquid dye. X-ray images are taken as the bladder fills and empties. The X-rays will show if there is any reverse flow of urine into the ureters and kidneys.