Near the time you ovulate each month, estrogen production from the ovaries stimulates mucus production by your cervix. Sperm must penetrate and swim through this mucus, then travel through the reproductive tract to reach the egg for fertilization. In some cases, there is an incompatibility between the sperm and the cervical mucus, causing the sperm to become immobile or die, thus preventing fertilization. The postcoital test (PCT) evaluates the interaction between the sperm and your cervical mucus at a time near ovulation to determine if an incompatibility exists. Abnormal mucus may occur because of infections, surgery or clomid therapy. The PCT is a poor predictor of pregnancy success, but may be useful to determine the need for intrauterine insemination. If it is done too early before ovulation or too late after, the results may be falsely abnormal.
The Reliability of the PostCoital Test