‘Rim’ and ‘ball’ nephrograms in intravenous urography are seen in –
**Core Concept**
Intravenous urography (IVU) is a radiographic imaging technique that involves the administration of a contrast medium to visualize the urinary system. The "rim" and "ball" nephrograms are terms used to describe specific appearances of the kidneys on IVU images.
**Why the Correct Answer is Right**
The "rim" nephrogram is seen in conditions where the renal cortex is preserved, but the renal medulla is obstructed. This appearance is classically seen in **pyelonephritis**, where the contrast medium outlines the renal cortex as a thin rim, while the renal medulla appears as a non-opacified area. The "ball" nephrogram, on the other hand, is seen in conditions where there is a significant loss of renal function, leading to a reduced or absent nephrogram. This appearance is classically seen in **acute tubular necrosis (ATN)**, where the renal cortex and medulla are both affected, resulting in a reduced or absent contrast excretion.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the described nephrograms. While it may be a condition affecting the urinary system, it does not specifically relate to the "rim" and "ball" appearances.
**Option B:** This option is incorrect because it does not accurately describe the conditions associated with the "rim" and "ball" nephrograms. While it may be a condition affecting the kidneys, it is not specifically related to the described appearances.
**Option C:** This option is incorrect because it does not accurately describe the conditions associated with the "rim" and "ball" nephrograms. While it may be a condition affecting the urinary system, it is not specifically related to the described appearances.
**Option D:** This option is incorrect because it does not accurately describe the conditions associated with the "rim" and "ball" nephrograms. While it may be a condition affecting the kidneys, it is not specifically related to the described appearances.
**Clinical Pearl / High-Yield Fact**
In IVU, the "rim" and "ball" nephrograms are indicative of specific conditions affecting the kidneys. Remember that the "rim" nephrogram is seen in pyelonephritis, while the "ball" nephrogram is seen in acute tubular necrosis. These appearances can provide valuable clues in the diagnosis of various renal conditions.
**Correct Answer: C. Acute tubular necrosis (ATN)**