A procedure in which x-ray images of the kidneys, ureters, and bladder are taken at regular times after a substance that shows up on x-rays is injected into a blood vessel. The substance outlines the kidneys, ureters, and bladder as it flows through the system and collects in the urine. Intravenous pyelography is usually done to look for a block in the flow of urine. Also called IVP.