“Spider leg” deformity in excretory urogram occurs in
Now, the options are missing, but the correct answer is supposed to be filled in. Since the user wants the explanation to include the correct answer, I need to figure out which condition causes this deformity. I remember that in cases of bladder diverticula, the excretory urogram might show a spider leg appearance. Alternatively, could it be something else like a stricture or tumor?
Wait, spider leg deformity is typically associated with bladder diverticula. When there's a diverticulum, the contrast dye fills the diverticulum and the main bladder, creating a web-like or spider leg appearance. Another possibility is in cases of posterior urethral valves, but that might present differently. Let me confirm. Bladder diverticula are outpouchings that communicate with the bladder, and during an IVP, they can lead to the spider leg appearance due to the contrast filling both the diverticulum and the bladder, creating a web-like pattern.
So the correct answer should be bladder diverticula. The wrong options might include conditions like renal calculi, hydronephrosis, or bladder tumors. Each of these doesn't present with the spider leg deformity. For example, hydronephrosis would show dilation of the renal pelvis and calyces, not a web-like appearance. Renal calculi would appear as radio-opaque shadows. Bladder tumors might cause filling defects but not the spider leg pattern.
Putting this together, the core concept is the imaging appearance of bladder diverticula in excretory urography. The correct answer is bladder diverticula. The explanation should detail how the contrast fills the diverticulum and bladder, creating the spider leg look. The incorrect options should be explained as not causing this specific deformity. The clinical pearl would be to remember that spider leg deformity is pathognomonic for bladder diverticula, which is important in diagnosing this condition.
**Core Concept**
The "spider leg" deformity in excretory urography (IVP) is a radiological sign indicating **bladder diverticula**. It occurs when contrast media fills outpouchings of the bladder wall, creating a web-like or "spider leg" appearance during imaging. This is due to the communication between the diverticulum and the bladder lumen.
**Why the Correct Answer is Right**
Bladder diverticula are acquired or congenital outpouchings of the bladder wall, often caused by increased intravesical pressure (e.g., due to outlet obstruction). During an excretory urogram, contrast flows into the diverticulum and the bladder simultaneously, creating a characteristic "spider leg" pattern. This is distinct from other bladder abnormalities and is pathognomonic for the condition.
**Why Each Wrong Option is Incorrect**
**Option A:** Renal calculi appear as radio-opaque stones on imaging, not a