Table of ContentsView AllTable of ContentsAnatomyRole in MenstruationRole in PregnancyWhat Is a Closed Cervix?
Table of ContentsView All
View All
Table of Contents
Anatomy
Role in Menstruation
Role in Pregnancy
What Is a Closed Cervix?
The cervical os is a narrow opening at each end of the cervix (which connects the vagina with the main body of the uterus via the endocervical canal).
The cervix is about an inch long but can vary in length and width during a woman’s lifetime.
CFCF / Wikimedia Commons
Anatomy of the Cervix
To describe the cervical os, it helps to first review theanatomy of the cervix. The cervix contains:
You can locate the external cervical os during a simpleself-exam. By inserting two (clean) fingers into the vagina, you can feel the cervix toward the back of the vaginal space.The cervix will feel round, while the cervical os will feel like a small donut with a hole or indentation in the middle.
Cervical Os and Menstruation
Throughout themenstrual cycle, the cervical os will open and close in conjunction with the various phases of menstruation. Depending on the stage, the position of the cervix changes, sometimes higher and sometimes lower.
During ovulation, the cervix is high and positioned closer to the top of the vagina.This change of position allows the cervical os to open more readily to allow sperm to enter. When ovulating, the cervical os is open and relaxed, and the surrounding cervix is high and soft with a feeling similar to pursed lips.
During the non-fertile stage of menstruation, the cervix is low and firm and the cervical os closes.Vaginal secretions become thicker and more acidic to protect against bacteria and other infectious agents.
Cervical Os and Pregnancy
After conception and the implantation of the fertilized egg in the uterus, the cervical os changes. This change is in response to both the stage of pregnancy and the growth of the developing fetus.
In the process of effacement, the internal and external os come closer together. As effacement and dilation progress, the healthcare provider or midwife uses the extent of the cervical opening to help make treatment decisions.
During the first stage of labor, uterine contractions become strong and regular, and the cervix dilates to more than 4 inches (10 centimeters).
In some cases, the cervical os will get abnormally narrow or close completely. This is a condition known as cervical stenosis.It is possible to be born with a closed cervix. It can also be a result of uterine surgery,endometriosis, scarring, cysts, or cervical cancer.
Symptoms can include periods that become more irregular or painful. A closed cervix can also cause infertility because sperm can’t travel into the uterus to fertilize an egg.
To diagnose a closed cervix, your gynecologist needs to perform a pelvic examination to see your cervix. If your os looks narrow or otherwise appears abnormal, they may try to pass a probe through it. If they can’t, you may get a diagnosis of cervical stenosis.
If you don’t have symptoms or are not trying to become pregnant, treatment is not always necessary for cervical stenosis.
But if you’re trying to get pregnant or have painful symptoms, your healthcare provider may recommend using cervical dilators.These are small devices placed in the cervix that slowly expand over time, stretching your cervix.
Summary
The cervical os is the opening in the cervix at each end of the endocervical canal. The external os is near the vagina, and the internal os is near the uterus.
A condition called cervical stenosis, or closed cervix, can cause painful periods. It may also cause infertility because the sperm can’t reach the egg. To correct this, a cervical dilator can help to open the cervix slowly over time.
10 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Cancer Institute.Anatomy of the female pelvis.Chen CY, Chen CP, Sun FJ.Assessment of the cervix in pregnant women with a history of cervical insufficiency during the first trimester using elastography.Acta Obstet Gynecol Scand. 2020;99(11):1497-1503. doi:10.1111/aogs.13942Deng H, Mondal S, Sur S, Woodworth CD.Establishment and optimization of epithelial cell cultures from human ectocervix, transformation zone, and endocervix optimization of epithelial cell cultures.J Cell Physiol. 2019;234(6):7683-7694. doi:10.1002/jcp.28049Planned Parenthood.Cervical health 101: exploring your cervix for health and pleasure.Dong M, Dong Y, Bai J, et al.Interactions between microbiota and cervical epithelial, immune, and mucus barrier.Front Cell Infect Microbiol. 2023;13:1124591. Published 2023 Feb 24. doi:10.3389/fcimb.2023.1124591Vink J, Myers K.Cervical alterations in pregnancy.Best Practice & Research Clinical Obstetrics & Gynaecology. 2018;52:88-102. doi:10.1016/j.bpobgyn.2018.03.007Nott JP, Bonney EA, Pickering JD, Simpson NAB.The structure and function of the cervix during pregnancy.Translational Research in Anatomy. 2016;2:1-7. doi:10.1016/j.tria.2016.02.001Moramazi F, Roohipoor M, Najafian M.Association between internal cervical os stenosis and other female infertility risk factors.Middle East Fertility Society Journal. 2018;23(4):297-299. doi:10.1016/j.mefs.2018.02.002Oh H, Park SB, Park HJ, et al.Ultrasonographic features of uterine cervical lesions.Br J Radiol. 2021;94(1121):20201242. doi:10.1259/bjr.20201242Kilpatrick C.Cervical stenosis.Merck Manual Professional.
10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Cancer Institute.Anatomy of the female pelvis.Chen CY, Chen CP, Sun FJ.Assessment of the cervix in pregnant women with a history of cervical insufficiency during the first trimester using elastography.Acta Obstet Gynecol Scand. 2020;99(11):1497-1503. doi:10.1111/aogs.13942Deng H, Mondal S, Sur S, Woodworth CD.Establishment and optimization of epithelial cell cultures from human ectocervix, transformation zone, and endocervix optimization of epithelial cell cultures.J Cell Physiol. 2019;234(6):7683-7694. doi:10.1002/jcp.28049Planned Parenthood.Cervical health 101: exploring your cervix for health and pleasure.Dong M, Dong Y, Bai J, et al.Interactions between microbiota and cervical epithelial, immune, and mucus barrier.Front Cell Infect Microbiol. 2023;13:1124591. Published 2023 Feb 24. doi:10.3389/fcimb.2023.1124591Vink J, Myers K.Cervical alterations in pregnancy.Best Practice & Research Clinical Obstetrics & Gynaecology. 2018;52:88-102. doi:10.1016/j.bpobgyn.2018.03.007Nott JP, Bonney EA, Pickering JD, Simpson NAB.The structure and function of the cervix during pregnancy.Translational Research in Anatomy. 2016;2:1-7. doi:10.1016/j.tria.2016.02.001Moramazi F, Roohipoor M, Najafian M.Association between internal cervical os stenosis and other female infertility risk factors.Middle East Fertility Society Journal. 2018;23(4):297-299. doi:10.1016/j.mefs.2018.02.002Oh H, Park SB, Park HJ, et al.Ultrasonographic features of uterine cervical lesions.Br J Radiol. 2021;94(1121):20201242. doi:10.1259/bjr.20201242Kilpatrick C.Cervical stenosis.Merck Manual Professional.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
National Cancer Institute.Anatomy of the female pelvis.Chen CY, Chen CP, Sun FJ.Assessment of the cervix in pregnant women with a history of cervical insufficiency during the first trimester using elastography.Acta Obstet Gynecol Scand. 2020;99(11):1497-1503. doi:10.1111/aogs.13942Deng H, Mondal S, Sur S, Woodworth CD.Establishment and optimization of epithelial cell cultures from human ectocervix, transformation zone, and endocervix optimization of epithelial cell cultures.J Cell Physiol. 2019;234(6):7683-7694. doi:10.1002/jcp.28049Planned Parenthood.Cervical health 101: exploring your cervix for health and pleasure.Dong M, Dong Y, Bai J, et al.Interactions between microbiota and cervical epithelial, immune, and mucus barrier.Front Cell Infect Microbiol. 2023;13:1124591. Published 2023 Feb 24. doi:10.3389/fcimb.2023.1124591Vink J, Myers K.Cervical alterations in pregnancy.Best Practice & Research Clinical Obstetrics & Gynaecology. 2018;52:88-102. doi:10.1016/j.bpobgyn.2018.03.007Nott JP, Bonney EA, Pickering JD, Simpson NAB.The structure and function of the cervix during pregnancy.Translational Research in Anatomy. 2016;2:1-7. doi:10.1016/j.tria.2016.02.001Moramazi F, Roohipoor M, Najafian M.Association between internal cervical os stenosis and other female infertility risk factors.Middle East Fertility Society Journal. 2018;23(4):297-299. doi:10.1016/j.mefs.2018.02.002Oh H, Park SB, Park HJ, et al.Ultrasonographic features of uterine cervical lesions.Br J Radiol. 2021;94(1121):20201242. doi:10.1259/bjr.20201242Kilpatrick C.Cervical stenosis.Merck Manual Professional.
National Cancer Institute.Anatomy of the female pelvis.
Chen CY, Chen CP, Sun FJ.Assessment of the cervix in pregnant women with a history of cervical insufficiency during the first trimester using elastography.Acta Obstet Gynecol Scand. 2020;99(11):1497-1503. doi:10.1111/aogs.13942
Deng H, Mondal S, Sur S, Woodworth CD.Establishment and optimization of epithelial cell cultures from human ectocervix, transformation zone, and endocervix optimization of epithelial cell cultures.J Cell Physiol. 2019;234(6):7683-7694. doi:10.1002/jcp.28049
Planned Parenthood.Cervical health 101: exploring your cervix for health and pleasure.
Dong M, Dong Y, Bai J, et al.Interactions between microbiota and cervical epithelial, immune, and mucus barrier.Front Cell Infect Microbiol. 2023;13:1124591. Published 2023 Feb 24. doi:10.3389/fcimb.2023.1124591
Vink J, Myers K.Cervical alterations in pregnancy.Best Practice & Research Clinical Obstetrics & Gynaecology. 2018;52:88-102. doi:10.1016/j.bpobgyn.2018.03.007
Nott JP, Bonney EA, Pickering JD, Simpson NAB.The structure and function of the cervix during pregnancy.Translational Research in Anatomy. 2016;2:1-7. doi:10.1016/j.tria.2016.02.001
Moramazi F, Roohipoor M, Najafian M.Association between internal cervical os stenosis and other female infertility risk factors.Middle East Fertility Society Journal. 2018;23(4):297-299. doi:10.1016/j.mefs.2018.02.002
Oh H, Park SB, Park HJ, et al.Ultrasonographic features of uterine cervical lesions.Br J Radiol. 2021;94(1121):20201242. doi:10.1259/bjr.20201242
Kilpatrick C.Cervical stenosis.Merck Manual Professional.
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