Excretory urography is contraindicated in:March 2011
**Core Concept**
Excretory urography, also known as intravenous urography (IVU), is an imaging technique that involves the injection of a radiopaque contrast agent to visualize the urinary system. This procedure is contraindicated in certain situations due to potential risks or complications.
**Why the Correct Answer is Right**
Excretory urography is contraindicated in patients with **renal failure** due to the accumulation of the contrast agent in the kidneys, which can lead to further renal impairment. The kidneys rely on a functioning glomerular filtration system to excrete the contrast agent, and in the presence of renal failure, this process is compromised. Furthermore, the contrast agent can cause a significant increase in the osmotic load, exacerbating the existing renal impairment.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because excretory urography is not contraindicated in patients with **pyelonephritis**. In fact, the procedure can be useful in identifying the site of infection and guiding treatment.
**Option B:** This option is incorrect because excretory urography is not contraindicated in patients with **obstructive uropathy**. The procedure can be useful in identifying the site and cause of obstruction.
**Option C:** This option is incorrect because excretory urography is not contraindicated in patients with **polycystic kidney disease**. The procedure can be useful in identifying the number and location of cysts.
**Clinical Pearl / High-Yield Fact**
It is essential to assess renal function before performing excretory urography, particularly in patients with a history of renal disease or those taking nephrotoxic medications.
**Correct Answer: A. Renal failure.**