Infertility Problems With Cervical Mucus

ByRobert W. Rebar, MD, Western Michigan University Homer Stryker M.D. School of Medicine
Reviewed/Revised Feb 2024

Abnormal cervical mucus can prevent sperm from entering the uterus, but this problem is rarely a major cause of infertility.

  • 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.)

Cervical mucus 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 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), 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) 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).

Did You Know...

  • Just before an egg is released (ovulation), mucus in the cervix changes consistency to allow sperm to enter the uterus.

Diagnosis of Cervical Mucus Problems

  • A doctor's evaluation

Doctors do a pelvic examination 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 and chlamydia.

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).

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