Cervical cancer screening is used to find changes in the cells of the cervix that could lead to cancer. The cervix is the opening to the uterus and is located at the top of the vagina. Screening includes cervical cytology (also called the Pap test or Pap smear) and, for some women, testing for human papillomavirus (HPV).
Most cases of cervical cancer are caused by infection with HPV. HPV is a virus that enters cells and can cause them to change. Some types of HPV have been linked to cervical cancer as well as cancer of the vulva, vagina, penis, anus, mouth, and throat. Types of HPV that may cause cancer are known as “high-risk types.”
HPV is passed from person to person during sexual activity. It is very common, and most people who are sexually active will get an HPV infection in their lifetime. HPV infection often causes no symptoms. Most HPV infections go away on their own. These short-term infections typically cause only mild (“low-grade”) changes in cervical cells. The cells go back to normal as the HPV infection clears. But in some women, HPV does not go away. If a high-risk type of HPV infection lasts for a long time, it can cause more severe (“high-grade”) changes in cervical cells. High-grade changes are more likely to lead to cancer.
It usually takes 3–7 years for high-grade changes in cervical cells to become cancer. Cervical cancer screening may detect these changes before they become cancer. Women with low-grade changes can be tested more frequently to see if their cells go back to normal. Women with high-grade changes can get treatment to have the cells removed.
Cervical cancer screening includes the Pap test and, for some women, an HPV test. Both tests use cells taken from the cervix. The screening process is simple and fast. You lie on an exam table and a speculum is used to open the vagina. The speculum gives a clear view of the cervix and upper vagina.
Cells are removed from the cervix with a brush or other sampling instrument. The cells usually are put into a special liquid and sent to a laboratory for testing:
For a Pap test, the sample is examined to see if abnormal cells are present.
For an HPV test, the sample is tested for the presence of 13–14 of the most common high-risk HPV types.