Prostate

Functions

Secretes alkaline fluid which constitutes ~30% of semen (with spermatozoa and seminal vesicle fluid) and protects sperm against acidic vaginal environment. This fluid is produced constantly, with the excess being expelled in urine.

Contains smooth muscles which help project sperm during ejaculation. These muscles also help in involuntary control of urine.

Anatomy

Complex exocrine gland surrounding the male urethra; located in the lower pelvis, anterior to the rectum and inferior to the bladder. 4x3x2cm, weighs 11-16g (though dimensions increase with age). The ejaculatory ducts join the urethra within the prostate at the seminal colliculus.

Anatomically divided into 4 lobes (distinct from zones!): anterior (isthmus), posterior, lateral, median.

Clinical

Benign Prostatic Hyperplasia (BPH) is enlargement of the prostate, in particular the Transition zone. BPH begins about age 30 but only becomes symptomatic (e.g. hesitancy, frequency, urge, nocturia) in 40-50% of men.

Digital Rectal Exams (DRE) can be used to differentiate BPH from malignant causes (53.2% specificity; 83.6% sensitivity), especially when PSA levels are taken.

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