Postcoital test is also known as Sims test, Huhner test or Sims-Huhner test. It is one of the few test carried out during infertilty diagnosis and treatment to determine the causes of infertility. Postcoital test is a fertility test where sperm and mucus of the cervix and it's action is examined. The postcoital test is generally done after sex, preferably within 24 hrs. And another crucial point to be noted is the time of ovulation of women. The women must be ovulating. Sample of cervical mucus is obtained from the women and how the sperm has interacted with it is analyzed. If the good quality of sperm is observed in test, then other cause of infertility is checked. If the quality of the sperm is low (ie. has many inactive and dead sperm), then sperm and mucus is incompatible.