One method of examining bladder function is by injecting dye that is visible on X-rays through a tube (catheter) to fill the bladder. X-rays are taken while the bladder is full and while the patient is urinating (voiding) to determine if fluid is forced out of the bladder through the urethra (normal) or up through the ureters into the kidney (vesicoureteral reflux). This study is usually done with the patient lying on an X-ray table.

Cystography is a detailed study of the bladder, which uses a dye and X-rays. A catheter is inserted into the bladder in which the dye flows. When the bladder is full, the catheter is removed and the X-rays are taken. X-rays are also taken when the bladder is empty. The test is performed to check for the integrity of the bladder, determine the cause of infections and check for tumors or stones.