The cervix is the lower portion of the uterus. It is approximately two inches long, and it's tubular in shape.

It widens during childbirth to allow for the passage of the baby. It also allows for the passage of menstrual fluid from the uterus, and sperm needs to travel through the cervix in order to reach the uterus.

The cervix is vulnerable to several health conditions, such as chronic inflammation, polyps, dysplasia, and cancer. Unfortunately, cervical conditions rarely present symptoms in the early stages; therefore, a regular Pap smear from a gynecologist is vital. A Pap smear can identify abnormal cervical changes long before they become cancerous.

Cervical cancer screening guidelines that were updated by the American Congress of Obstetricians and Gynecologists (ACOG) in February 2016 suggest:

  • Women should have their first Pap smear at age 21. (The old guidelines recommended that women have their first Pap three years after becoming sexually active or at age 21—whichever came first.)
  • Women aged 21–29 years should have a Pap test alone every 3 years. HPV testing is not recommended.
  • Women aged 30–65 years should have a Pap test and an HPV teest (co-testing) every 5 years (preferred). It also is acceptable to have a Pap test alone every 3 years.
  • Women age 65 or older should stop having cervical cancer screenings if they do not have a history of moderate or severe abnormal cervical cells or cervical cancer, and if they have had either three negative Pap test results in a row or two negative co-test results in a row within the past 10 years, with the most recent test performed within the past 5 years.
  • Women who have had a hysterectomy should ask their doctor about whether or not they still need screening. The answer depends on several factors, including whether the cervix was removed, why the hysterectomy was needed, and whether there's a history of moderate or severe cervical cell changes or cervical cancer. Even if the cervix is removed at the time of the hysterectomy, cervical cells can still be present at the top of the vagina. If you have a history of cervical cancer or cervical cell changes, you should continue to have screenings for 20 years after the time of your surgery. 

Anatomy of the Cervix

Several key components contribute to cervical function. These areas of the cervix are often discussed during pregnancy, Pap smears, and colposcopy exams. It is important to become familiar with them so you can understand possible changes occurring in your cervix. This knowledge will also help you understand tests, like the Pap smear or colposcopy.

  • Endocervical Canal: This is the potential space in the center of the tube of tissue that is the cervix. During a colposcopy, the doctor may take a sample of cells in the endocervical canal. This is called an endocervical curettage (ECC).
  • Ectocervix: This is the lower part of the cervix that protrudes into the vagina.
  • Internal Os: This part of the cervix is closest to the uterus. During pregnancy and childbirth, you may hear the doctor speak about the "os."
  • External Os: This is the opening of the ectocervix.
  • Transformation Zone: This is also called the "TZ" for short. This is the area of the cervix where cervical dysplasia commonly occurs. The transformation zone is often discussed during a colposcopy exam.