An intravenous pyelogram is a type of X-ray examination specifically designed to study the kidneys, bladder, and ureters (the tubes which carry urine from the kidneys to the bladder). After iodine-based contrast dye is injected intravenously, a series of images are taken at timed intervals. The kidneys are responsible for removing contrast from the blood and collecting it in urine. Abnormalities in the appearance of the kidneys or ureters, distribution of contrast within a kidney, asymmetry in the amount of contrast in each kidney, or defects in the collecting systems can be identified and are suggestive of particular diseases and conditions.