Correct Answer: C. Median
The median lobe of the prostate forms the uvula vesicae, a small projection into the bladder trigone. This lobe is unique because it develops from the urethral epithelium and grows upward into the bladder between the two ejaculatory ducts. The uvula vesicae is clinically significant in Indian urology practice because benign prostatic hyperplasia (BPH) of the median lobe can cause bladder outlet obstruction and acute urinary retention—a common presentation in elderly men. The median lobe is the only prostatic lobe that projects into the bladder lumen; the other lobes (anterior, posterior, and lateral) surround the urethra externally. During digital rectal examination (DRE), the median lobe cannot be palpated because it lies above the rectum. This anatomical distinction is critical for understanding why median lobe BPH may not be detected on DRE alone and why transurethral resection of the prostate (TURP) is the gold standard for symptomatic median lobe enlargement in Indian clinical settings.
Why the other options are wrong
A. Posterior — The posterior lobe lies behind the urethra and is palpable on digital rectal examination. It does not project into the bladder; instead, it forms the bulk of the prostate felt on DRE. This is the most commonly enlarged lobe in BPH and is accessible to palpation, making it clinically detectable—unlike the uvula vesicae. B. Lateral — The lateral lobes (right and left) flank the urethra and are also palpable on DRE. They contribute to urethral compression in BPH but do not form any intravesical projection. The uvula vesicae is specifically an intravesical structure, which the lateral lobes are not. D. Anterior — The anterior lobe is the smallest and lies anterior to the urethra, forming part of the ventral aspect of the prostate. It is not palpable on DRE and does not project into the bladder. The anterior lobe is clinically insignificant in BPH and has no relationship to uvula vesicae formation.
High-Yield Facts
- Uvula vesicae is formed exclusively by the median lobe of the prostate and projects into the bladder trigone.
- The median lobe is not palpable on DRE because it lies above the rectum; only posterior and lateral lobes are felt on examination.
- Median lobe BPH causes bladder outlet obstruction and acute urinary retention despite a normal-feeling prostate on DRE—a common diagnostic trap in Indian clinical practice.
- TURP (transurethral resection) is the gold standard for symptomatic median lobe enlargement; open prostatectomy is reserved for very large glands (>45 g).
- The uvula vesicae is a normal anatomical landmark visible on cystoscopy and is exaggerated in median lobe hyperplasia.
Mnemonics
Median = Intravesical Median lobe → Midline → Middle of bladder (uvula vesicae). Only the median lobe grows into the bladder; all others grow around the urethra. DRE Paradox Digital Rectal Exam feels posterior + lateral lobes only. If prostate feels normal on DRE but patient has retention → suspect median lobe BPH. This is the classic Indian urology board trap.
NBE Trap
NBE pairs "prostate lobe" with "palpable on DRE" to trap students into choosing posterior or lateral. The key discriminator is that uvula vesicae is intravesical (inside the bladder), not extraprostatic—only the median lobe achieves this.
Clinical Pearl
A 68-year-old man presents with acute urinary retention; DRE shows a small, firm prostate. Cystoscopy reveals an enlarged uvula vesicae. This is classic median lobe BPH—a common scenario in Indian urology OPDs where DRE alone misses the diagnosis. TURP is curative.
_Reference: Bailey & Love Ch. 71 (Prostate); Robbins Ch. 20 (Urinary System)_