Semen analysis evaluates a man's sperm and semen to determine the cause of infertility or to confirm the success of a vasectomy. Semen is the thick yellow-white male ejaculate containing sperm; sperm are the male sex cells that fertilize the female egg (ovum) and contain the genetic information that the male will pass on to a child.

Abnormalities of sperm and semen can cause male infertility, and semen analysis is an initial step in investigating why a couple has been unable to conceive a child. Vasectomy is an operation done to sterilize a man by stopping the release of sperm into semen. Success of vasectomy is confirmed by the absence of sperm in semen.

The semen analysis test is usually done manually, though computerized test systems are available. Many laboratories base their procedures on standards published by the World Health Organization (WHO).

The volume of semen...