The presence of anti-sperm antibodies (ASA) is a cause of infertility in men and women. Antibodies against sperm can prevent their motility through the female reproductive tract or prevent the process of fertilization. It has been shown that both males and females can make antibodies that react with human sperm. In males, for example, ASA can be detected in seminal plasma and serum, and are also located on the surface of sperm, which cannot be detected in a routine semen analysis. The female may produce ASA, which may be found in circulating blood or produced in the cervical mucus. ASA has usually been found in homosexual males and in cases of testicular trauma, varicocele mumps or orchids, spinal cord injury, congenital absence of the vas and vasectomy