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Abnormal Cervical Mucus

by Robert W. Rebar, MD

Abnormal cervical mucus may impair fertility by inhibiting penetration or increasing destruction of sperm.

Normally, cervical mucus is stimulated to change from thick and impenetrable to thin and stretchable by an increase in estradiol levels during the follicular phase of the menstrual cycle. Abnormal cervical mucus may

  • Remain impenetrable to sperm around the time of ovulation

  • Promote sperm destruction by facilitating influx of vaginal bacteria (eg, due to cervicitis)

  • Contain antibodies to sperm (occasionally)

Abnormal mucus rarely impairs fertility significantly, except in women with chronic cervicitis or cervical stenosis due to prior treatment for cervical intraepithelial neoplasia.


Women are examined to check for cervicitis and cervical stenosis. Unless they have one of these disorders, postcoital testing of cervical mucus to determine whether viable sperm are present (which used to be routine during infertility evaluation) is unnecessary. Postcoital testing is not useful.


Treatment may include intrauterine insemination or drugs to thin the mucus (eg, guaifenesin). Neither treatment has been proved effective.

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