The prostate is located deep in the pelvis and sits at the top of the penis. Behind it is the rectum (back passage) and above it is the bladder.

A tube called the urethra passes right through the middle of the prostate. The urethra carries urine and semen out through the penis.

The prostate gland is about the size of a walnut, but it tends to get bigger as you get older. By the age of 80, nearly all men have an enlarged prostate.