Question

What investigation should be done for a prostatic nodule in a 60 year old man?

• A. Expressed prostatic secretion analysis
• B. CT scan pelvis
• C. Transrectal ultrasound (TRUS)
• D. MRI

Hint:

Think about which test both images the prostate closely and can guide a biopsy needle.

Answer 1

The Correct Option is C

Step 1: Understand the clinical scenario.
A prostatic nodule found on digital rectal exam in an older man raises concern for prostate cancer. The next step is imaging that can show the nodule clearly and also guide a biopsy.

Step 2: Recall the imaging options for the prostate.
CT scan and MRI can show the prostate but do not give the fine local detail needed to target a small nodule, and CT is poor at showing the zonal anatomy of the gland.

Step 3: Explain why transrectal ultrasound is preferred.
Transrectal ultrasound (TRUS) places the probe close to the prostate through the rectum, so it gives a clear, high resolution picture of the gland. It shows the nodule directly and lets the surgeon guide a needle into it for biopsy in the same sitting, so it works as both a diagnostic tool and a biopsy guide.

Step 4: Rule out the other options.

(A) Expressed prostatic secretion analysis: This checks for infection (prostatitis), not cancer, and cannot assess a nodule.

(B) CT scan pelvis: Poor at showing prostate zonal detail and cannot guide an accurate targeted biopsy.

(D) MRI: Useful for staging once cancer is already confirmed, but it is not the first test for a newly found nodule, and it does not double as a biopsy guide the way TRUS does.

Step 5: Final answer.
The correct first investigation for a prostatic nodule is transrectal ultrasound, since it images the gland closely and guides a needle biopsy in one visit.
\[ \boxed{\text{Transrectal ultrasound (TRUS)}} \]