**Core Concept**
A cystogram is a radiographic examination of the urinary bladder, typically performed to assess its structure and function. It is a crucial diagnostic tool in evaluating conditions such as vesicoureteral reflux, bladder trauma, and post-void residual urine.

**Why the Correct Answer is Right**
Cystography involves the introduction of a contrast agent into the bladder, which allows for visualization of the bladder's lumen and walls. This imaging modality is essential in diagnosing and managing conditions like urinary incontinence, bladder outlet obstruction, and fistulas. The procedure can be performed via the transurethral route or percutaneously.

**Why Each Wrong Option is Incorrect**
**Option A:** Vesicoureteral reflux is a valid indication for cystogram, as it helps in diagnosing the condition and assessing its severity. Therefore, option A is incorrect because it is a correct indication for cystogram.

**Option B:** Bladder trauma is another valid indication for cystogram, as it helps in assessing the extent of injury and guiding further management. Therefore, option B is incorrect because it is a correct indication for cystogram.

**Option D:** Post-void residual urine is a valid indication for cystogram, as it helps in assessing the bladder's emptying mechanism and guiding management of urinary retention. Therefore, option D is incorrect because it is a correct indication for cystogram.

**Clinical Pearl / High-Yield Fact**
Cystography is a useful diagnostic tool in evaluating conditions that may require surgical intervention, such as bladder diverticula or bladder stones. A high index of suspicion and prompt referral to a urologist are essential in managing these conditions.

**Correct Answer: A.**