oiding cystourethrogram and voiding cystourethrography are abbreviated VCUG or VCU. A test to examine the bladder and urethra while the bladder fills and empties. A radiopaque liquid (that can be seen on x-ray) is placed in the bladder through a catheter. The bladder is filled until the patient urinates. Radiographs (x-rays) are usually taken before, during, and after voiding. This test can reveal abnormalities of the inside of the urethra and bladder. The test can also determine whether the flow of urine is normal when the bladder empties.