What is a Pap test?
A Pap test (sometimes called a Pap smear) is a way to examine cells collected from the cervix, or the opening of the womb (located at the top of the vagina), for the presence of:
- Abnormal cells
Why is a Pap test suggested to women?
A Pap test, along with a pelvic exam, is an important part of a woman's routine health care because it may detect abnormalities that can lead to 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)
Who should have Pap tests?
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 may also be performed, in which the cervix is coated with an iodine solution. The iodine stains healthy cells brown, while abnormal cells maintain their typical white or yellow color.
A biopsy may be performed in which the physician removes a small amount of cervical tissue for examination by a pathologist. This is the only sure way to determine whether the abnormal cells indicate cancer.
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 (NCI), the American Cancer Society (ACS), and the American College of Obstetricians and Gynecologists (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.
- Experts recommend waiting approximately three years following the initiation of sexual activity because transient human papillomavirus (HPV) infections and cervical cell changes that are not significant are common and it takes years for a significant abnormality or cancer to develop. Cervical cancer is extremely rare in women under the age of 25.
- Women should have a Pap test at least once every three years.
- 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.
- ACS and ACOG recommend that at or after age 30, women who have had three normal test results in a row may get screened every two to three years. However, women with certain risk factors such as human immunodeficiency virus (HIV) 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, are sexually inactive, and have had no abnormal Pap tests in the last 10 years may decide, upon consultation with their healthcare 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. Women who have had a hysterectomy without the removal of the cervix should continue to have screening according to these general guidelines.
- Women should seek expert medical advice about when they should begin screening, how often they should be screened, and when they can discontinue cervical screenings, especially if they are at higher than average risk of cervical cancer due to factors such as HIV infection or infection with the HPV virus.
Liquid-based cytology - a Pap test alternative:
In the past few years, a newer way of testing cervical cells for abnormalities has gained acceptance in the medical community. This procedure is called liquid-based cytology. Approved by the US Food and Drug Administration (FDA), the test 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. Though the procedure, called Thinprep, AutoCyte, or SurePath, costs more than a Pap test, studies show that these tests may require fewer repeat tests and detect more early-stage lesions. Consult your physician for more information.