The uterine cervix or cervix is the lower part of the uterus, thanks to which the vagina is connected to the uterine cavity.
Its function is basically acting as a barrier to sperm penetration on their way towards fertilizing the egg. It is also the path through which menstrual bleeding exits the body.
Between 5 and 10% of couples experiencing some type of infertility are diagnosed with what is known as cervical factor infertility.
Cervical factor is a leading cause of female infertility when there exist anatomical and/or functional abnormalities in the cervix. These alterations interfere with the adequate migration of spermatozoa towards the uterus and the Fallopian tubes in their attempt to reach the egg.
The cervix or cervix uteri secretes a thick mucus known as cervical mucus or vaginal discharge, which consistency and appearance varies depending on the phase of the menstrual cycle the woman finds herself at the moment, due to hormonal action.
The following are the main functions of the cervical mucus:
- Allowing the passage of sperm while the woman is ovulating
- Protecting the sperm from the vagina and its environment
- Selecting the healthiest spermatozoa by leaving behind those without fertilizing potential
Under the influence of estrogens—about halfway through the menstrual cycle—, vaginal discharge acquires a watery appearance, and is usually present in abundance. This allows sperm penetration and paves the way for sperm to reach the egg. Conversely, it gets thicker, viscous, and less abundant after ovulation, which is to say, when progesterone release begins.
A woman may experience cervical abnormalities at two levels: on the one hand, functional abnormalities and, on the other, anatomical abnormalities.
Functional cervical abnormalities
Mucus features such as consistency, amount, etc. may hinder the right functioning of the cervix. This may block the entrance of sperm into the uterine cavity and therefore lead to female infertility.
As an example, women whose estrogen release during ovulation is insufficient tend to produce thicker vaginal discharge than usual during these days, therefore making it difficult for sperm to enter the uterus.
The consumption of certain medicines, infections, the presence of anti-sperm antibodies, and severe hormonal imbalances or endocrine disorders are the main causes as to why vaginal discharge may vary its qualities and work differently.
Anatomical cervical abnormalities
Obstructive processes such as polyps, cysts, etc. are included as well as temporary or surgical trauma that cause tears, fistulas, or incontinence of the woman's internal and external orifices, with the subsequent functional alteration of the same one.
On the other hand, cervicitis or inflammation of the cervix, whether it is acute or chronic, may lead to female infertility as well. It is commonly caused by microbial infections such as chlamydia, Trichomonas vaginalis, candida infection, or mycoplasma.
Acute cervicitis is a common inflammation during the puerperal period. Cervical stenosis, agenesis, and bicervical uterus are also frequent cervical anatomical alterations that may lead to fertility problems among women.
The main diagnostic tests carried out to determine the presence of cervical factor infertility are:
- The postcoital test (PCT): it is used to assess the presence or absence of motile sperm in the woman's vaginal discharge after having had sexual intercourse.
- In vitro immunological tests: apart from evaluating the characteristics of the cervical mucus and the seminal fluid, the presence of anti-sperm antibodies is also studied in both substances, as well as the spermatozoa potential to penetrate the cervical mucus.
Both diagnostic tests allow the specialist to examine the characteristics of a woman's cervical mucus in order to determine whether the passage of sperm is possible or something is blocking it.
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