Enlarged prostate gland. Coloured X-ray of the pelvis of a male patient showing an enlarged prostate gland. The enlargement is seen as two dark indentations at the bottom of the bladder (white, lower centre). The prostate sits below the bladder. It produces a fluid that forms part of the semen. Enlargement (hypertrophy) of the gland obstructs the neck of the bladder, impairing urination, which may in turn damage the kidneys. It may be caused by cancer of the prostate. Treatment includes surgical removal of part of the gland or the prescription of drugs that cause it to shrink.