IVP uses intravenous radiopaque contrast to visualize which structures and evaluate renal function by analyzing the flow of contrast over time.

• A. Uses ultrasound to produce real-time images of the kidneys
• B. Uses oral dye to assess bladder capacity
• C. Uses IV radiopaque contrast to visualize the kidneys, ureters, bladder, and renal pelvis; evaluates renal function by contrast flow over time
• D. Measures kidney enzyme levels in blood

Answer: (C)

Intravenous pyelography relies on injecting radiopaque contrast into the bloodstream so the kidneys can filter and excrete it, allowing the urinary tract to be outlined on X-ray. The contrast flows from the kidneys into the renal pelvis, down the ureters, and into the bladder, and serial images over time show how quickly and completely the contrast moves through the system. This provides both anatomical detail of the kidneys, ureters, renal pelvis, and bladder and functional information about renal excretion. The other options don’t fit because ultrasound uses real-time imaging without IV contrast, oral dye wouldn’t visualize the urinary tract in this way, and measuring kidney enzymes in blood assesses function but not imaging of the urinary tract.