Intravenous urography primarily visualizes which organ?

• A. Kidneys
• B. Liver
• C. Spleen
• D. Bladder

Answer: (A)

Intravenous urography uses an injected contrast that is filtered by the kidneys and excreted into the urine, making the urinary tract visible on radiographs. The kidneys are the structures whose anatomy and function are being assessed first and most clearly, with the renal parenchyma and collecting system (calyces andrenal pelvis) outlining prominently during the nephrogram and pyelogram phases. As the contrast travels down, the ureters and then the bladder fill, but the primary organ visualized by this study is the kidneys. The liver and spleen aren’t part of the urinary excretion pathway, and while the bladder will appear in later phases, it’s the kidneys that define the exam’s focus.