The cervix or cervix uteri (Latin: neck of the uterus) is the lower part of the uterus in the human female reproductive system. In a non-pregnant woman, the cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape. The narrow, central cervical canal runs along its entire length, connecting the uterine cavity and the lumen of the vagina. The opening into the uterus is called the internal os, and the opening into the vagina is called the external os. The lower part of the cervix, known as the vaginal portion of the cervix (or ectocervix), bulges into the top of the vagina. The cervix has been documented anatomically since at least the time of Hippocrates, over 2,000 years ago.
The cervical canal is a passage through which sperm must travel to fertilize an egg cell after sexual intercourse. Several methods of contraception, including cervical caps and cervical diaphragms aim to block or prevent the passage of sperm through the cervical canal. Cervical mucus is used in several methods of fertility awareness, such as the Creighton model and Billings method, due to its changes in consistency throughout the menstrual period. During vaginal childbirth, the cervix must flatten and dilate to allow the fetus to progress along the birth canal. Midwives and doctors use the extent of the dilation of the cervix to assist decision-making during childbirth.
The endocervical canal is lined with a single layer of column-shaped cells, while the ectocervix is covered with multiple layers of cells topped with flat cells. The two types of epithelia meet the squamocolumnar junction. Infection with the human papillomavirus (HPV) can cause changes in the epithelium, which can lead to cancer of the cervix. Cervical cytology tests can often detect cervical cancer and its precursors, and enable early successful treatment. Ways to avoid HPV include avoiding sex, using condoms, and HPV vaccination. HPV vaccines, developed in the early 21st century, reduce the risk of cervical cancer by preventing infections from the main cancer-causing strains of HPV.
Cervix: The cervix is the lower, narrow part of the uterus (womb). The uterus, a hollow, pear-shaped organ, is located in a woman's lower abdomen, between the bladder and the rectum. The cervix forms a canal that opens into the vagina, which leads to the outside of the body.
The word "cervix" comes straight from Latin for "neck".
The cervix is the lower end of the womb (uterus). It is at the top of the vagina. It is about 2 inches long. The cervical canal passes through the cervix. It allows blood from a menstrual period and a baby (fetus) to pass from the womb into the vagina.
The cervical canal also allows sperm to pass from the vagina into the uterus.
Conditions that affect the cervix include:
- Cervical infection
A Pap smear is a screening test to check for cancer of the cervix.
The cervix is a cylinder-shaped neck of tissue that connects the vagina and uterus. The cervix is made of cartilage covered by smooth, moist tissue, and is about 1 inch across. There are two main portions of the cervix:
- The part of the cervix that can be seen from inside the vagina during a gynecologic examination is known as the ectocervix. An opening in the center of the ectocervix, known as the external os, opens to allow passage between the uterus and vagina.
- The endocervix, or endocervical canal, is a tunnel through the cervix, from the external os into the uterus.
The overlapping border between the endocervix and ectocervix is called the transformation zone.
The cervix produces cervical mucus that changes in consistency during the menstrual cycle to prevent or promote pregnancy.
During childbirth, the cervix dilates widely to allow the baby to pass through. During menstruation, the cervix opens a small amount to permit passage of menstrual flow.
- Cervical cancer: Most cervical cancer is caused by infection by the human papillomavirus (HPV). Regular Pap tests can prevent cervical cancer in most women.
- Cervical incompetence: Early opening, or dilation, of the cervix during pregnancy that can lead to premature delivery. Previous procedures on the cervix are often responsible.
- Cervicitis: Inflammation of the cervix, usually caused by infection. Chlamydia, gonorrhea, and herpes are some of the sexually transmitted infections that can cause cervicitis.
- Cervical dysplasia: Abnormal cells in the cervix that can become cervical cancer. Cervical dysplasia is frequently discovered on Pap test.
- Cervical intraepithelial neoplasia (CIN): Another name for cervical dysplasia.
- Cervix polyps: Small growths on the part of the cervix where it connects to the vagina. Polyps are painless and usually harmless, but they can cause vaginal bleeding.
- Pelvic inflammatory disease (PID): Infection of the cervix, known as cervicitis, may spread into the uterus and fallopian tubes. Pelvic inflammatory disease can damage a woman's reproductive organs and make it more difficult for her to become pregnant.
- Human papillomavirus (HPV) infection: Human papillomaviruses are a group of viruses, including certain types that cause cervical cancer. Less dangerous types of the virus cause genital and cervical warts.
- Pap test: A sample of cells is taken from a woman's cervix and examined for signs of changes. Pap tests may detect cervical dysplasia or cervical cancer.
- Cervical biopsy: A health care provider takes a sample of tissue, or biopsy, from the cervix to check for cervical cancer or other conditions. Cervical biopsy is often done during colposcopy.
- Colposcopy: A follow-up test for an abnormal Pap test. A gynecologist views the cervix with a magnifying glass, known as a colposcope, and may take a biopsy of any areas that do not look healthy.
- Cone biopsy: A cervical biopsy in which a cone-shaped wedge of tissue is removed from the cervix and examined under a microscope. Cone biopsy is performed after an abnormal Pap test, both to identify and to remove dangerous cells in the cervix.
- Computed tomography (CT scan): A CT scanner takes multiple X-rays, and a computer creates detailed images of the cervix and other structures in the abdomen and pelvis. CT scanning is often used to determine whether cervical cancer has spread, and if so, how far.
- Magnetic resonance imaging (MRI scan): An MRI scanner uses a high-powered magnet and a computer to create high-resolution images of the cervix and other structures in the abdomen and pelvis. Like CT scans, MRI scans can be used to look for the spread of cervical cancer.
- Positron emission tomography (PET scan): A test to look for spread or recurrence of cervical cancer. A solution, known as a tracer solution, containing a mildly radioactive chemical is injected into the veins. The PET scan takes pictures as this solution moves through the body. Any areas of cancer take up the tracer and "light up" on scanner images.
- HPV DNA test: Cervical cells can be tested for the presence of DNA from human papillomavirus (HPV). This test can identify whether the types of HPV that can cause cervical cancer are present.
- Cervical cerclage: In women with cervical incompetence, the cervix can be sewn closed. This can prevent early opening of the cervix during pregnancy, which can cause premature delivery.
- Antibiotics: Medications that can kill the bacteria that causes infections of the cervix and reproductive organs. Antibiotics may be taken orally or given through a vein, or intravenously, for serious infections.
- Cryotherapy: An extremely cold probe is placed against abnormal areas on the cervix. Freezing kills the abnormal cells, preventing them from becoming cervical cancer.
- Laser therapy: A high-energy laser is used to burn areas of abnormal cells in the cervix. The abnormal cells are destroyed, preventing them from becoming cervical cancer.
- Cervical cancer vaccine: To prevent cervical cancer, a vaccine against certain strains of the human papillomavirus (HPV) is recommended for most adolescent girls and young women.
- Chemotherapy: Cancer medications that are usually injected into a vein. Chemotherapy is usually given for cervical cancer that is believed to have spread.
- Total Hysterectomy: Surgical removal of the uterus and cervix. If cervical cancer has not spread, hysterectomy can offer a complete cure.
- Cone biopsy: A cervical biopsy that removes a cone-shaped wedge of tissue from the cervix. Because a large portion of the cervix is removed, cone biopsy can help prevent or treat cervical cancer.
- Loop electrosurgical excision procedure (LEEP): An electrified wire loop is touched against abnormal cells in the cervix. The electrical current destroys the cells, preventing or treating cervical cancer.
- Radiation therapy: Using radioactive energy to kill cervical cancer cells. Radiation therapy is given as a beam from outside the body or in small pellets implanted in the cervix, known as brachytherapy.