How do doctors do an X-ray of the bladder and urethra while I urinate?

A voiding cystourethrogram is performed while you are lying down on your back while a film of your abdomen and pelvic area is taken. Dye is placed into your bladder through a catheter. As your bladder is filling up with the dye, X-rays are taken in various positions and various time intervals. The catheter is then removed and additional X-rays are taken while you urinate into a container. Once your bladder is empty, a final X-ray is taken.