Cervical Factor Infertility
The tip of the uterus that extends into the vagina is called the cervix. It is through the cervix that menstrual blood flows outward. During most of the month, thick mucus plugs the opening into the uterus. Around time of ovulation, a rising estrogen level makes the cervical mucus become thinner and thus easier for sperm to swim up into the uterus.
Some women may have abnormally thick cervical mucus which can make it harder for conception but this is rare. A test known as a post-coital test can be performed within 6 hours of intercourse just prior to ovulation to see if the mucus is thin and stretchy, and to see if motile sperm are present within the mucus as seen under a microscope. The presence of at least one motile sperm and stretchy cervical mucus to about 10 centimeters are the parameters for a normal post-coital test (PCT). The problem is that the results of the PCT are poorly correlated with successful pregnancy. Moreover, many women having an abnormal PCT, really do not have a mucus problem but the test was likely performed after ovulation when the mucus rapidly thickens from progesterone production and the sperm are then unable to penetrate the mucus. Many women with an abnormal PCT will have a normal one if the test is repeated with proper timing.
Women really having cervical mucus problems include those women who were exposed to DES while their mother was pregnant with them and women having extensive surgery on the cervix. Typically, a laser conization for an abnormal pap smear or a LEEP is not sufficient enough to cause this amount of damage. Medications such as clomiphene citrate may thicken cervical mucus in about 15% of women.
Some women also have an abnormal narrowing of the cervical opening called cervical stenosis. This can interfere with both infertility testing and procedures. Cervical stenosis can usually be successfully treated with a minor outpatient surgical procedure known as cervical dilatation.
Finally, the treatment for most cervical factor infertility is either intrauterine insemination (IUI) or in vitro fertilization (IVF). Because these treatments are commonly used anyway, many fertility specialists no longer perform tests such as the PCT.