Azoospermia is defined as the complete absence of sperm cells in semen and affects approximately 1% of all men. The male reproductive system is made up of the testes or testicles, seminal ducts, scrotum, prostate, epididymis, vas deferens and penis. Sperm that is produced in the testicles flows through the epididymis, vas deferens, seminal ducts and out through the penis. It is carried along its journey by semen, which is a thick white liquid produced by the prostate gland.
Azoospermia may have different causes. Pre-testicular azoospermia is caused by abnormalities in the hypothalamus, pituitary gland or the testicles whereas post-testicular azoospermia is caused by an obstruction or due to problems with ejaculation. A better way to categorize azoospermia is to classify it as either obstructive or non-obstructive. This allows for a more effective determination of treatment options as patients with non-obstructive azoospermia may have different genetic problems.