Benign Prostatic Hypertrophy: Anatomy & Relations

(i) Anatomical Basis of Urinary Problems

The difficulty in urine passage experienced by the 56-year-old male is directly related to the prostate gland’s anatomical position and its enlargement. The prostate surrounds the prostatic urethra, the portion of the urethra that passes through the prostate gland. BPH causes the prostate to expand, compressing the prostatic urethra. This compression creates urethral obstruction, increasing resistance to urine flow. The obstruction leads to several consequences:

• Increased Bladder Pressure: The bladder must generate greater force to overcome the obstruction.
• Bladder Wall Hypertrophy: Chronic increased pressure leads to thickening of the bladder wall.
• Incomplete Bladder Emptying: Residual urine remains in the bladder after voiding, predisposing to urinary tract infections.
• Straining: The patient strains to initiate and maintain urine flow due to the increased resistance.

The location of the prostate, inferior to the bladder and anterior to the rectum, means that its enlargement directly impacts the urethra, the primary pathway for urine flow. The prostatic capsule itself limits the expansion, leading to compression rather than diffuse enlargement.

(ii) Relations of the Prostate Gland

The prostate gland has extensive relations with various pelvic structures. These can be described as follows:

• Superiorly: The base of the prostate is related to the urinary bladder and the pubic symphysis. The ampulla of the vas deferens joins the ejaculatory duct as it enters the prostate.
• Inferiorly: The apex of the prostate rests on the deep perineal fascia, between the urogenital diaphragm and the rectum.
• Anteriorly: The pubic bones and the pubic symphysis.
• Posteriorly: The rectal ampulla, separated by the Denonvilliers’ fascia. This fascia is clinically important as it allows for surgical access to the prostate.
• Laterally: The levator ani muscles (puborectalis and iliococcygeus) and the internal obturator muscles. Neurovascular bundles (prostatic plexus) run along the lateral aspects of the prostate.

Understanding these relations is crucial for surgical interventions targeting the prostate, as damage to adjacent structures can lead to significant complications like urinary incontinence or erectile dysfunction.

(iii) Blood Supply and Lymphatic Drainage of the Prostate Gland

The prostate gland receives a rich blood supply and has a complex lymphatic drainage pattern.

Blood Supply

The arterial supply is derived from:

• Inferior Vesical Artery: The primary source, arising from the internal iliac artery.
• Middle Rectal Artery: Contributes to the posterior aspect of the prostate.
• Prostatic Branch of the Obturator Artery: Supplies the lateral aspects.

These arteries form a vascular plexus within the prostate gland. Venous drainage follows the arterial pathways, ultimately draining into the internal iliac veins.

Lymphatic Drainage

Lymphatic drainage is particularly important in the context of potential prostate cancer spread. The prostate’s lymphatic drainage follows several routes:

• Internal Iliac Lymph Nodes: The primary drainage pathway.
• Sacral Lymph Nodes: Drainage from the posterior aspect.
• External Iliac Lymph Nodes: Some drainage may reach these nodes.
• Obturator Lymph Nodes: Drainage from the lateral aspects.

The lymphatic drainage pattern explains why regional lymph node assessment is crucial in the staging of prostate cancer.