The post coital (after intercourse) infertility test is sometimes used to evaluate how sperm interacts with the cervical mucus. The couple has normal intercourse, using no lubricants, and the female comes to HRC within 24 hours. A sample of her cervical mucus is examined under the microscope.

Normal, motile sperm should be seen in the sample. If numerous, inactive or "dead" sperm are seen, it could indicate an antigen antibody reaction. Sometimes the female's immune system incorrectly identifies sperm as invading pathogens and seeks to destroy it in the same manner as bacteria or viruses. Rarely, a man may produce antibodies to his own sperm.

If female antibodies are present, intrauterine insemination (IUI) may be a good treatment alternative. In vitro fertilization (IVF) might also be an option for the couple depending upon many factors including age, previous treatments, and many other variables.