Problems with cervical mucus are not usually a major cause of infertility, but they may be a factor in women who have a cervical infection or scar tissue in the cervix (cervical stenosis).
Doctors do a pelvic examination to check for infection and a cervical canal that is narrowed or closed because of scar tissue.
Infections and scar tissue, if present, are treated.
(See also Overview of Infertility Overview of Infertility Infertility is usually defined as the inability to achieve a pregnancy after 1 year of regular sexual intercourse without birth control. Frequent intercourse without birth control usually results... read more 
.)
Cervical mucus Uterus and cervix is secreted by glands in the cervix (the lower part of the uterus that opens into the vagina). Normally, this mucus is thick and impenetrable to sperm until just before release of an egg (ovulation). Then, just before ovulation, the mucus becomes clear and elastic (because the level of the hormone estrogen increases). As a result, sperm can move through the mucus into the uterus to the fallopian tubes, where fertilization can take place.
Some women use fertility awareness methods Fertility Awareness Methods of Contraception Fertility awareness methods involve identifying which days a woman is likely to be fertile during her menstrual cycle. This information can be used to increase the chance of becoming pregnant... read more to prevent pregnancy or to try to become pregnant. These methods include checking the cervical mucus daily to detect the time when ovulation occurs.
Abnormal mucus may do the following:
Not change as it normally does at ovulation, making pregnancy unlikely
Allow bacteria in the vagina, usually those that cause infection in the cervix (cervicitis Cervicitis Cervicitis is inflammation of the cervix (the lower, narrow part of the uterus that opens into the vagina). It may be caused by an infection or another condition. Cervicitis is often caused... read more ), to enter the uterus, sometimes resulting in the destruction of sperm
Contain antibodies to sperm, which kill sperm before they can reach the egg (a rare problem)
However, problems with cervical mucus rarely impair fertility significantly, except in women who have a chronic cervical infection or a cervical canal that has been narrowed or closed (called cervical stenosis Cervical Stenosis Cervical stenosis is narrowing or closing of the passageway through the cervix (the lower part of the uterus). Cervical stenosis often causes no symptoms. Cervical stenosis may cause menstrual... read more ) because of scar tissue. (The cervical canal is the channel in the cervix through which sperm enter and menstrual blood exits.) Scar tissue is usually caused by a surgical procedure, such as one done to treat a precancerous abnormality of the cervix (cervical dysplasia Cervical Cancer 
).
Diagnosis of Cervical Mucus Problems
A doctor's evaluation
Doctors do a pelvic examination Pelvic Examination For gynecologic care, a woman should choose a health care practitioner with whom she can comfortably discuss sensitive topics, such as sex, birth control, pregnancy, and problems related to... read more to see if the cervical canal is narrow or closed and to check for infection. If women have an abnormal discharge from their vagina (which may indicate infection) or are at risk for a cervical infection, a sample of the discharge is taken from the cervix with a swab and is tested for gonorrhea Gonorrhea Gonorrhea is a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae, which infect the lining of the urethra, cervix, rectum, or throat, or the membranes that cover... read more 
and chlamydia Chlamydia and Other Nongonococcal Infections Chlamydial infections include sexually transmitted infections of the urethra, cervix, and rectum that are caused by the bacteria Chlamydia trachomatis. These bacteria can also infect... read more 
.
Treatment of Cervical Mucus Problems
Treatment of infections or scar tissue, if present
If a cervical infection is diagnosed, it is treated with antibiotics. If cervical stenosis is detected, it may be treated with a procedure to dilate (widen) the cervix.
Some women with abnormal cervical mucus are treated by placing semen directly in the uterus to bypass the mucus (intrauterine insemination Intrauterine insemination Assisted reproductive technologies involve working with sperm and eggs or embryos in a laboratory (in vitro) with the goal of producing a pregnancy. (See also Overview of Infertility.) If treatment... read more 
).
