Enlargement of the prostate, or prostatic hyperplasia, occurs in the migratory zone of the prostate.
The prostate gland consists of a central band, a peripheral band, an anterior fibromuscular region, and a migratory zone around the urethra. Prostatic hyperplasia occurs in the migratory zone, and the hyperplastic tissue appears as multiple nodules that gradually increase in size. The hyperplastic gland squeezes and atrophies the peripheral glands to form a surgical envelope of the prostate, which is clearly demarcated from the hyperplastic gland and can be easily separated during surgery.
Prostatic hyperplasia causes obstruction of the bladder outlet and compensatory hypertrophy of the bladder, forming a trabecular diverticulum or pseudodiverticulum. If the obstruction is prolonged, the bladder loses its compensatory ability, the contractility is weakened, and residual urine occurs because it cannot be emptied completely. As the amount of residual urine increases, chronic urinary retention as well as overflow incontinence can occur.
Patients with prostate enlargement should seek prompt medical attention to avoid urinary retention or incontinence.