How often do women think about their cervix? For most, it’s probably once a year while the gynecologist is scraping a few cells from it as part of an annual Pap smear.
But what exactly is a cervix and what does it do? First, it’s part of the female reproductive system. The National Institutes of Health (NIH) describe it as the lower end of the uterus. It is located at the top of the vagina and is about one inch long.
In a WomensHealth.About.com article, the cervix forms the neck of the uterus and opens into the vagina which is also called the endocervical canal. The narrow opening of the cervix is called the os. The cervical os allows menstrual blood to flow out from the vagina during menstruation. The os also gives passage to sperm as it passes from the vagina to uterus.
What about the size of cervical opening? Dr. Adelaide Nardone, clinical instructor at the Brown University School of Medicine, tells BabyZone.com, it depends on whether the woman has had a vaginal delivery or not. "If a woman has never had a baby, her cervical opening is very small, in some cases as small as a pinhead, but large enough to allow for menstrual blood to flow out and to allow for the insertion of a cytobrush (used for Pap smears). If a woman has had a vaginal delivery, the external opening of the cervix can be described as a small 'slit' or 'fish mouth'."
About.com says the cervix is covered by the epithelium which is made of a thin layer of cells. Epithelial cells are either squamous or columnar. Squamous cells are flat and scaly, while columnar cells form similar to what they sound like, columns.
The cervix may be out of sight, out of mind most of the time; but during pregnancy and labor, it takes center stage.
BabyZone.com says during pregnancy, the cervical os remains closed and the opening is blocked with a mucus plug. This both protects and keeps the fetus in place. WomensHealth.About.com says another important function of the cervix is when a woman goes into labor her cervix dilates, or widens, to allow the passage of the fetus from the uterus to the vagina.
According to Dr. Nardone in BabyZone.com, "Once labor ensues, the cervix must be able to yield to the intrauterine pressure and contractions and undergo dilatation and effacement. The main component of the cervix is collagen and this provides its firm consistency during gestation."
Reviewed July 21, 2011
by Michele Blacksberg R.N.
Edited by Jody Smith