Final answer:
An intravenous pyelogram is a radiographic contrast study primarily focused on the kidneys, which are crucial for filtering blood and producing urine.
Step-by-step explanation:
The intravenous pyelogram is the most commonly used contrast study of the kidneys. The kidneys are a pair of bean-shaped structures located posterior to the liver in the peritoneal cavity, and they are responsible for filtering the blood and forming urine. Each kidney has more than a million nephrons performing this filtration process. The urine then travels through paired kidneys, the ureter, the urinary bladder, and finally the urethra.