A semen analysis is used to determine whether a man might be infertile—unable to get a woman pregnant. The semen analysis consists of a series of tests that evaluate the quality and quantity of the sperm and the environment they reside in, the semen. The semen analysis also can be used to count sperm after a man has had a vasectomy, a procedure that prevents sperm from being released within the ejaculate and that is considered a permanent method of birth control (99.9%) when performed by an experienced surgeon. A semen analysis measures the quantity and quality of the fluid released during ejaculation. It evaluates both the liquid portion, called semen or seminal fluid, and the microscopic, moving cells called sperm. Sample: Semen (sperm) Reference: – – – Frequency: Once a week