About Pap Test

by National Cancer Institute

1. What is a Pap test?

The Pap test (sometimes called a Pap smear) is a way to examine cells collected from the cervix (the lower, narrow end of the uterus). The main purpose of the Pap test is to find abnormal cell changes that may arise from cervical cancer or before cancer develops.

2. What is a pelvic exam?

In a pelvic exam, the uterus, vagina, ovaries, fallopian tubes, bladder, and rectum are felt to find any abnormality in their shape or size. During a pelvic exam, an instrument called a speculum is used to widen the vagina so that the upper portion of the vagina and the cervix can be seen.

3. Why are a Pap test and pelvic exam important?

A Pap test and pelvic exam are important parts of a woman's routine health care because they can detect abnormalities that may lead to invasive cancer of the cervix. These abnormalities can be treated before cancer develops. Most invasive cancers of the cervix can be prevented if women have Pap tests regularly. Also, as with many types of cancer, cancer of the cervix is more likely to be treated successfully if it is detected early.

4. Who performs a Pap test?

Doctors and other specially trained health care professionals, such as physician assistants, nurse midwives, and nurse practitioners, may perform Pap tests and pelvic exams. These individuals are often called clinicians.

5. How is a Pap test done?

A Pap test is simple, quick, and painless; it can be done in a doctor's office, a clinic, or a hospital. While a woman lies on an exam table, the clinician inserts a speculum into her vagina to widen it. A sample of cells is taken from the cervix with a wooden scraper and/or a small cervical brush. The specimen (or smear) is placed on a glass slide and preserved with a fixative, or is rinsed in a vial of fixative, and is sent to a laboratory for examination.

6. How often should a woman have a Pap test?

Women should talk with their clinician about when and how often they should have a Pap test. Current general guidelines recommend that women have a Pap test at least once every 3 years, beginning about 3 years after they begin to have sexual intercourse, but no later than age 21. Experts recommend waiting about 3 years after the start of sexual activity to avoid overtreatment for common, temporary abnormal changes. It is safe to wait 3 years, because cervical cancer usually develops slowly. Cervical cancer is extremely rare in women under age 25.

Women ages 65 to 70 who have had at least three normal Pap tests and no abnormal Pap tests in the last 10 years may decide, after talking with their clinician, to stop having Pap tests. Women who have had a hysterectomy (surgery to remove the uterus and cervix) do not need to have a Pap test, unless the surgery was done as a treatment for precancer or cancer.

7. When should the Pap test be done?

A woman should have this test when she is not menstruating; the best time is between 10 and 20 days after the first day of the last menstrual period. For about 2 days before a Pap test, she should avoid douching or using vaginal medicines or spermicidal foams, creams, or jellies (except as directed by a physician). These may wash away or hide abnormal cells.

8. How are the results of a Pap test reported?

Most laboratories in the United States use a standard set of terms called the Bethesda System to report test results. Under the Bethesda System, Pap test samples that have no cell abnormalities are reported as "negative for intraepithelial lesion or malignancy." Samples with cell abnormalities are divided into the following categories:

ASC — atypical squamous cells. Squamous cells are the thin flat cells that form the surface of the cervix. The Bethesda System divides this category into two groups:

1. ASC-US-atypical squamous cells of undetermined significance. The squamous cells do not appear completely normal, but doctors are uncertain about what the cell changes mean. Sometimes the changes are related to HPV infection (see Question 13). ASC-US are considered mild abnormalities.

2. ASC-H-atypical squamous cells cannot exclude a high-grade squamous intraepithelial lesion. The cells do not appear normal, but doctors are uncertain about what the cell changes mean. ASC-H may be at higher risk of being precancerous.

AGC — atypical glandular cells. Glandular cells are mucus-producing cells found in the endocervical canal (opening in the center of the cervix) or in the lining of the uterus. The glandular cells do not appear normal, but doctors are uncertain about what the cell changes mean.

AIS — endocervical adenocarcinoma in situ. Precancerous cells are found in the glandular tissue.

LSIL —low-grade squamous intraepithelial lesion. Low-grade means there are early changes in the size and shape of cells. The word lesion refers to an area of abnormal tissue. Intraepithelial refers to the layer of cells that forms the surface of the cervix. LSILs are considered mild abnormalities caused by HPV infection.

HSIL — high-grade squamous intraepithelial lesion. High-grade means that there are more marked changes in the size and shape of the abnormal (precancerous) cells, meaning that the cells look very different from normal cells. HSILs are more severe abnormalities and have a higher likelihood of progressing to invasive cancer.

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