Cervical Mucus

5% of All Infertility

Abnormalities of cervical mucus play a major role in approximately 5% of all infertility problems. Understand that at the time of intercourse, the semen is deposited in the upper vagina and into the mucus. The sperm then have to swim through the cervical mucus where they are then propelled through the uterus and out into the fallopian tubes.

Evaluation of the cervical mucus is done at the same time that the woman’s menstrual cycle is being tracked. The cervical mucus is receptive to the sperm only at the time of ovulation. When a woman is at the time of ovulation, the cervical mucus is thin, clear, watery and very stretchable. When put under the microscope and allowed to dry, the mucus takes on the appearance of a fern leaf. This phenomenon, called “ferning” is another way to assess the quality of the cervical mucus.

There are many problems in evaluating cervical mucus and especially its relationship to infertility. First of all, there are many studies in the literature calling in to question how important abnormalities of cervical mucus truly are in causing infertility. A study published several years ago from Canada came to the conclusion that post-coital tests are a waste of time and should not be done. While I think this may be an extreme position, it is inappropriate to blame every infertility problem on cervical mucus and spend a great deal of time trying to diagnosis and treat cervical mucus problems while at the same time missing the real cause of that couple’s infertility.

Another study was published in the British Medical Journal in the summer of 1998 looking at post coital tests and pregnancy rates. This was a randomized, controlled, prospective study and it showed that the post coital test had no bearing on that woman’s subsequent ability to become pregnant. This is consistent with other studies which have shown essentially the same thing.

Another problem is the fact that there is no universally accepted definition as to what constitutes a normal post-coital test. While there may be a general consensus, there is no one standard and every infertility specialist has his or her own definition as to what is normal. The World Health Organization (WHO) does have a standard, but not everyone adheres to it. Many people feel that as long as there is at least 1 moving sperm seen, the test is “normal”.

A normal post coital test tells me that the man is capable of having normal intercourse and is capable of depositing reasonably normal semen into the upper vagina. It tells me that the woman is capable of producing normal cervical mucus. It tells me that the sperm are capable of living in that mucus. It therefore may help to identify specific problems. However, please understand that there is no good evidence that treating cervical mucus problems per se substantially improves a couple’s chances of conceiving. While there are occasional couples for whom the cervical mucus problem is the only reason for their infertility, I am very reluctant to blame a woman’s infertility problem solely on poor cervical mucus. Whenever I encounter a couple with a persistently abnormal post coital test, particularly in the face of a normal semen analysis, I always look for other causes of that couple’s infertility.

Nonetheless, it can be a valuable test if interpreted properly. When the woman is being tracked through her menstrual cycle, and she is near the time of ovulation, she is asked to have intercourse prior to her office visit. This, of course, creates its own problems since some men cannot perform on demand and under pressure. Ideally, the couple should be seen 6 to 10 hours following intercourse.

To perform the test the woman comes to the office and a small sample of the cervical mucus is removed. This is a totally painless procedure. The mucus is then placed on a slide and examined under the microscope.

When you look through a microscope, the area that you see is a circle and this circle is called a “microscopic field”. Depending upon the degree of magnification, that field may take in a larger or smaller amount of the slide.

When looking at the cervical mucus under high magnification (a high power field) you should see at least 5 and preferably 10 or more actively moving sperm in each field for the test to be normal.

Not only must the sperm be moving, they must be moving forward with some “purpose” to their motion. Sperm that are simply moving around back and forth or only wiggling their tails may be moving but it is not a normal movement.

All these factors are taken into consideration in evaluating the normalcy of the test.

In order for the test to be truly interpretable, it must be done at the time of ovulation. Ultrasound and hormone levels are used to determine that the timing is indeed correct. The most common reason for an abnormal post coital test is simply the fact that it was not done at the proper time of the menstrual cycle.

In addition to being properly timed, you really only expect to get a normal post coital test if the husband has a normal semen analysis and the wife’s cervical mucus is also of good quality. A post coital test performed in a situation where it is known that the husband has poor semen quality does have some predictive value. There is some evidence in the medical literature that a post coital test may be a better predictor of future pregnancy than the semen analysis. Certainly it is very gratifying to see a relatively good post coital test in a couple where the husband’s quality is subfertile. On the other hand, a properly timed poor post coital test with a normal semen analysis and good mucus may indicate a significant problem, often suggesting significant anti-sperm antibodies.

It is also important to determine that the quality of the cervical mucus is good. Unfortunately this is done by very crude means such as looking at the mucus and seeing the quality of the fern pattern. More sophisticated tests are available on a research basis but are not available for clinical practice.

If a couple is found to have a persistently abnormal post coital test, various therapies can be tried. However, their success is still variable and no definitive answers are yet available.

We know that estrogen stimulates the production of cervical mucus. Estrogen is sometimes, therefore, given to women with poor mucus in the hopes of improving the quality of the mucus. Unfortunately, most women with poor mucus have normal estrogen levels. Furthermore, giving a dose of estrogen high enough to stimulate good mucus production would also interfere with ovulation.

Women being treated with Clomiphene (Serophene or Clomid) will occasionally develop poor mucus from the Clomiphene itself (though not as often as commonly believed). Clomiphene also interferes with the development of the endometrium as well. These women were often given estrogen along with the Clomiphene in an attempt to improve the quality of the mucus. Unfortunately, such an approach does not work.

To get around this, Pergonal is often used as a treatment for poor cervical mucus, particularly in women who need Clomiphene, and it is often very successful. Pergonal will also improve the quality of the endometrium.

Another technique that is used to bypass poor cervical mucus is Intra-Uterine Insemination (IUI) . This is probably where intrauterine insemination has its greatest usefulness and its most proven effectiveness even though most evidence does indicate that IUI improves pregnancy rates regardless of the cause so long as the woman has at least one open and relatively undamaged tube.

As I have discussed in other pamphlets, for those couples with either “unexplained infertility” or for those couples who are going through ovulation stimulation with IUI as an alternative or as a preliminary step to IVF, the question has been asked whether a normal post coital test eliminates the need for IUI. Some studies have shown a better pregnancy rate with IUI and other studies have shown that properly timed intercourse is probably just as good although most studies do tend to lean toward IUI as the better therapy.

This has more than academic importance because of the restrictions that some insurance companies place on IUI. Because of some of these restrictions, couples may be forced to choose between what is economically feasible compared to what is medically better. As an example, Pennsylvania Blue Shield has adopted the position that not only will they not pay for IUI, they will not pay for any of the drugs or monitoring during an IUI cycle. From both a medical and an economic perspective this makes absolutely no sense whatsoever. It is about as stupid a restriction as I have ever seen an insurance company impose. The numbers clearly show that Pennsylvania Blue Shield will have to pay out over twice as much money to achieve a pregnancy by denying couples IUI than they would if they agreed to pay for it.

As fewer couples are covered by Pennsylvania Blue Shield and are being switched into other plans, some of which cover IUI, this becomes a less important issue. Nonetheless, it does clearly illustrate the absurd position that some insurance companies take when it comes to the coverage they provide for infertility therapy.

In summary then, I do believe that the post coital test has value in the evaluation of the infertile couple but its importance has often been exaggerated. I believe the post coital test is important not because of its predictive value but because it may permit a better choice of therapies.

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