Postcoital tests in fertility testing
Infertility is a disease that affects around 8 – 15% of couples. Routine semen analysis provides useful information about sperm production, sperm motility and viability. However, it lacks information on the sperm function.
A complete assessment should provide information on all the processes including those after the sperms are deposited into the female genital tract until the sperm delivers the genetic material to the egg. Sperm function tests are thought to be second tier tests. Fertility specialists may advise in cases of unexplained infertility.
What is postcoital test (PCT)?
Postcoital test (PCT) helps us understand the interaction between the sperm and the cervical mucous. It also indicates whether the sperms can move upwards into the womb and reach the egg. In addition to the fertility tests already available, the search is on for the test that can help us differentiate between male fertility, male subfertility and male infertility.
The PCT looks into how the sperms are passing the cervical mucus in the female tract. A normal postcoital test would be where 10 to 20 sperms are seen under a high magnification microscope in a number of microscopic fields. These sperms should also show forward progression or what is also called ‘progressive motility’. This is assessed under 400 high-power microscope fields. The test has to be done in the middle of the female menstrual cycle.
If the sperms seem paralysed or show side-to-side shaking movement, then this is suggestive of injury to the sperms from the anti-sperm antibodies. An abnormal PCT result suggests but does not prove, cervical factor infertility from anti-sperm antibodies.
It is difficult to do the test and the results lack reliability. Also, problems with regular ovulation and poor coital technique may affect the result of a postcoital test. The test is invalid in presence of cervical infection. In the case of an abnormal result, the test is not reproducible if done on another occasion.
There have been other alternative in vitro penetration tests attempted using chemicals. The in vitro penetration tests are still in the early stages of development. They will need more validation before they can be recommended for routine clinical application.
The current role of PCT is largely historical. Given its significant limitations, the in vitro sperm penetration test may have clinical value in some patients with unexplained infertility.