Courtesy of Intermountain Medical Imaging, Boise, Idaho.
A cystourethrogram is an X-ray test that takes pictures of your bladder and urethra while your bladder is full and while you are urinating. A liquid called contrast material is injected into your bladder through your urethra. The urethra is the tube that carries urine from the bladder to the outside of the body. The contrast material shows up on X-rays as a dark spot.
This test may be used to check how well your bladder works or to find the cause of problems with your urinary tract (kidneys, ureters, bladder, and urethra). Normally, urine is made in the kidneys and travels down the ureters to the bladder where it is stored. When the bladder is full, urine is passes out of the body through the urethra.
Figure 1 shows an X-ray of contrast material abnormally flowing from the bladder up the ureter (vesicoureteral reflux). Figure 2 is a later X-ray showing more abnormal backflow.