(PCT) A test of: (1) receptiveness of the cervical mucus to sperm; and (2) sperm motility -- both of which are needed for the test to be a positive test. It's essential that the test be done to coincide with ovulation, tested with a urinary LH kit or measurements of serum estradiol (high), serum LH (preferably high) and serum progesterone (still low), because the job description of the cervical mucus at other times is to be impenetrable to sperm (i.e. the PCT will be negative for normal reasons).

Estimation of sperm antibodies in the cervical mucus. The presence of these antibodies can cause negative tests of cervical mucus-sperm interaction, including a negative postcoital test.

Inflammation of the cervix, usually because of infection. Sperm might or might not have trouble getting through the cervical mucus: this can be tested with a postcoital test. Occasionally cervicitis can mean that there is endometritis and salpingitis, in which case there will usually be pus present in the cervix. A cause of intermenstrual bleeding and postcoital bleeding. Clinically there might be contact bleeding when taking a PAP smear.

Serial transvaginal ultrasounds of the ovary during the follicular phase to track the growth of one or more tertiary follicles, accompanied usually by serial estimations of serum estradiol, serum LH and serum progesterone, for the two-fold purpose of estimating follicular maturity (to time intercourse, a mid-cycle-dependent investigation such as a postcoital test, or an egg retrieval) and identifying the onset of the LH-surge, which can affect the timing of the intervention. Sometimes accompanied by injection of human chorionic gonadotropin to trigger ovulation at a precisely anticipated time.

In medicine generally it may be best for tests to be negative (like tests for brain tumors or tests for sexually transmitted diseases such as HIV -- as for 'histories', compare negative history), but this is not always so in infertility. Infertility tests are generally better if they're positive, like the postcoital test, tests for ovulation, tests for tubal patency, and (not least) a pregnancy test.

In medicine, it might generally be best for tests to be negative (like tests for brain tumors or tests for sexually transmitted diseases, such as HIV -- as for medical histories, compare positive history) -- but not so in infertility. Infertility tests, such as the postcoital test, tests for ovulation, tests for tubal patency, and (not least) a pregnancy test, are generally better if they're positive.

Infertility for which no obvious cause has been found after the following tests have been done with normal results: a sperm count or postcoital test; a test of ovulation, such as a serum progesterone that is satisfactorily high; and a laparoscopy (used to show that the tubes are open and that there is no endometriosis or other obvious abnormality). Although a hysterosalpingogram (HSG) can substitute for laparoscopy in excluding blockage of the fallopian tubes, an HSG can miss peritubal adhesions and will miss endometriosis. Infertility should not be considered unexplained unless a thorough, careful laparoscopy has been done.