A Pap test (sometimes called a Pap smear) is a way to examine cells collected from the cervix, or the “mouth” of the womb (located at the top of the vagina), for the presence of:
- Abnormal cells
A Pap test, along with a pelvic exam, is an important part of a woman’s routine health care because it may detect abnormalities before they become invasive cancer. Most invasive cancers of the cervix can be detected early if women have Pap tests and pelvic examinations regularly. As with many types of cancer, cancer of the cervix is more likely to be successfully treated if it is detected early.
The Pap test is useful for detecting not only cancerous cells, but also other cervical and vaginal abnormalities including dysplasia (precancerous cells) and inflammation. Inflammation may be caused by:
- Yeast infections
- Trichomoniasis infections
- Medications or other chemicals
- Miscarriage (or abortion)
A woman should always consult with her physician about when and how often a Pap test and pelvic examination should be performed.
According to the National Cancer Institute, the American Cancer Society (ACS) and the American College of Obstetrics and Gynecology (ACOG), general guidelines include:
- Cervical cancer screening should begin approximately three years after a woman begins having sexual intercourse, but no later than at 21 years old.
- The ACS and ACOG recommend annual cervical cytology screening with regular Pap tests or biannual (every two years) screening with liquid-based tests (Thinprep) until age 30. Women under age 30 have a higher likelihood than older women of acquiring high-risk types of HPV that cause premalignant cervical disease, which should be ruled out before extending the testing intervals.
- The ACS and ACOG recommend that, at or after age 30, women may get screened every two to three years if:
- They have had three normal test results in a row previously;
- They are at a low risk otherwise; and
- They are in a monogamous relationship.
However, women with certain risk factors such as human immunodeficiency virus infection, a weak immune system, in utero DES exposure or a previous diagnosis of cervical cancer may need more frequent screening.
- Women 65 to 70 years of age who have had at least three normal Pap tests and no abnormal Pap tests in the last 10 years may decide, upon consultation with their health care provider, to stop cervical cancer screening.
- Women who have had a total hysterectomy (removal of the uterus and cervix) do not need to undergo cervical cancer screening, unless the surgery was done as a treatment for cervical precancer or cancer.
A new way of testing cervical cells for abnormalities is gaining acceptance in the medical community. Though the cost of the procedure, call Thinprep, is higher than a conventional Pap test, studies show that Thinprep may require fewer repeat test and detects more precancerous lesions. Approved by the U.S. Food and Drug Administration, Thinprep is a liquid-based procedure in which cells from the cervix are put into a vial of liquid instead of being “smeared” onto a slide. The liquid is then filtered and only the cervical cells are placed onto a slide for examination.
Thinprep Paps are collected in the same way as a conventional Pap, during a routine exam, but are processed differently. This test may not be covered by all third-party payors. Check with your physician to see if this test is available.
According to the National Cancer Institute, when the Pap test shows an ambiguous or minor abnormality, the test is usually repeated to ensure accuracy.
If the test shows a significant abnormality, a colposcopy may be performed (using an instrument called a colposcope) to examine the vagina and the cervix.
A Schiller test also may be performed in which the cervix is coated with an iodine solution.
A biopsy may be performed in which the physician removes a small amount of cervical tissue for examination by a pathologist. This procedure is the only sure way to determine whether the abnormal cells indicate cancer.