The postcoital test: what is it and how is it useful?
The postcoital test was originally conceived as a way to determine whether cervical factors caused sterility. As it has been demonstrated over the years that only in a very small percentage of patients are cervical causes the only causes of infertility, it is a technique that has fallen into disuse.
What is the postcoital test (PCT) or the Sims-Huhner test?
First described by Sims in 1866 and modified thereafter by Huhner, this test involves the study of a patient’s cervical mucus after sexual intercourse without contraception. This test should be performed in the periovulatory phase, that is, close to ovulation and between 6 and 12-16 hours after sexual intercourse. This is when a sample of cervical mucus should be obtained in order to study its characteristics (volume, elasticity, consistency, the existence of any inflammatory or infectious processes) as well as the presence and quantity of motile spermatozoa.
The test does not entail any more discomfort than a normal gynaecological examination – the use of a speculum is required – but obtaining cervical mucus is not painful in itself.
What are the results of a PCT?
The presence of mucus with oestrogenic characteristics and the discovery of motile sperm is reassuring. On the other hand, if no spermatozoa were to be found or if the spermatozoa were not to be motile, this would be considered abnormal. If the latter were to be the case, before making any decisions as to the type of treatment, the recommendation would be to check the sperm quality by means of a seminogram (semen analysis) and to make sure that the woman is in the periovulatory stage.
During the 1990s, this test was also used to determine the presence in the cervical mucus of antibodies that fight against spermatozoa, but after several studies showed that the presence of such antibodies did not in fact worsen the results of fertility treatments, this determination is no longer usually performed.
When is a post-coital test currently indicated?
For many years, a post-coital test was a fundamental part of a basic fertility examination, but nowadays its usefulness is controversial, and the world’s leading fertility groups do not routinely recommend its use. The reasons for this paradigm shift are:
- its lack of reproducibility, i.e., this test performed by two different people at two different times on the same couple can yield opposite results.
- Its scarce concordance with the possibility of achieving pregnancy or, in other words, although the test reveals altered parameters, it has not been demonstrated that this has an influence on the couple’s chances of achieving pregnancy.
Therefore, nowadays, it would only be indicated in couples where there is no other way to obtain a semen sample for analysis, either due to personal or religious reasons.