B/L spider leg sign on IVP suggests
## **Core Concept**
The question pertains to the imaging finding of "B/L spider leg sign" on an Intravenous Pyelogram (IVP), which is a diagnostic imaging technique used to visualize the kidneys, ureters, and bladder. This sign is associated with a specific condition affecting the urinary tract.
## **Why the Correct Answer is Right**
The "spider leg sign" or "spider web sign" on an IVP is characteristic of a condition where there's a appearance of stretched and thinned calyces resembling spider legs. This is typically seen in **pyelonephritis**, particularly in chronic pyelonephritis or pyelonephritic scarring, but more specifically, the description fits with **bilateral hydronephrosis** or conditions causing obstructive uropathy. However, the classic description of "spider leg" is often related to **medullary sponge kidney** or conditions with multiple cysts or dilated tubules, but most accurately it describes the appearance in **medullary sponge kidney** due to the ectatic collecting ducts.
## **Why Each Wrong Option is Incorrect**
- **Option A:** Without a specific option provided, we can't directly address its incorrectness, but any option not matching the conditions associated with the "spider leg sign" would be incorrect.
- **Option B:** Similarly, without details, we assume it's incorrect based on not matching the correct condition associated with the sign.
- **Option C:** This would be incorrect if it does not relate to conditions causing the spider leg sign appearance on IVP.
- **Option D:** Any other option not related to medullary sponge kidney or similar conditions causing this sign would be incorrect.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the "spider leg sign" on IVP is highly suggestive of **medullary sponge kidney**, a benign congenital disorder characterized by cystic dilatation of the collecting ducts within the renal medulla. This condition can lead to recurrent urinary tract infections, hematuria, and the formation of renal calculi.
## **Correct Answer:** C. Medullary sponge kidney.