What is the purpose of a postcoital test (PCT)?

What is the purpose of a postcoital test (PCT)?

A post-coital test involves taking a sample of the mucus from the cervical canal between eight and twelve hours after intercourse around the time of ovulation (days 13-14 in a 28 day cycle). The mucus is placed on a glass slide and then examined under a microscope. You should have the opportunity of looking down the microscope for yourselves.

There is debate as to the value of the test. A positive test will show reasonable numbers of actively motile sperm and confirms that ovulation is taking place, that the male partner is producing reasonable quality sperm and that the mucus is not inhibiting sperm movement. A positive test also confirms that intercourse is resulting in semen being deposited on the cervix.

It has been estimated that 6% of infertility is related to coital difficulties and it seems entirely appropriate to me that this should be checked by such a simple test particularly as other fertility tests and treatment can be expensive. The cervical mucus may be hostile to sperm even during ovulation and cervical factor has been considered to be responsible in up to 10% of couples presenting with infertility. Whilst a positive test is reassuring, a negative test is more difficult to evaluate. On several occasions we have seen a negative test in a conception cycle. Another argument against the post-coital test is that the most common form of treatment, whether the test is positive or not, is intrauterine insemination (Q10.23).

The majority of our patients find it reassuring to know that this potential cause for otherwise unexplained infertility has been checked. There are occasions when the post-coital test identifies an unexpected coital problem. The test may be of greater value in units that use treatments specifically for the cervical factor such as pre-ovulatory oestrogen or pre-coital sodium bicarbonate douching (Q10.22)

In vitro cross testing, utilizing donor mucus and sperm can indicate the origin of an abnormal PCT. A drop of the partner's sperm and donor sperm are placed on a glass slide in contact with the woman's cervical mucus and also with donor mucus from another woman. Penetration of the mucus is evaluated microscopically. These tests have become less popular now that we have more advanced treatments.

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