**Core Concept**
The patient is presenting with signs of urethral injury, likely a traumatic urethral stricture or rupture, following a motor vehicle accident. The presence of a scrotal hematoma, blood at the urethral meatus, and a high-riding prostate are indicative of urethral disruption.

**Why the Correct Answer is Right**
Given the clinical presentation, the next step in management is to perform a suprapubic catheterization to establish urinary drainage and prevent further complications such as urinary ascites and sepsis. This is a crucial step to avoid further injury to the urethra during attempted catheterization. The patient's high-riding prostate and blood at the urethral meatus suggest that a traditional urethral catheterization may not be feasible.

**Why Each Wrong Option is Incorrect**

* **Option A:** Immediate CT scan of the abdomen and pelvis. While imaging may be necessary for further evaluation, it is not the immediate next step in management of a suspected urethral injury.
* **Option B:** Attempt to pass a urethral catheter. Given the patient's clinical presentation, this may exacerbate the injury and is not recommended.
* **Option C:** Administer pain medication and observe. While pain management is important, it does not address the underlying issue of urethral injury and the need for urinary drainage.

**Clinical Pearl / High-Yield Fact**
In cases of suspected urethral injury, a suprapubic catheter should be inserted to avoid further injury to the urethra during attempted catheterization. This is a critical step in preventing complications and ensuring proper urinary drainage.

**Correct Answer:** D. Suprapubic catheterization.