Pap Smear Procedure Information on MedicineNet.com

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Pap Smear

Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

What is a Pap smear?

A Pap smear (also known as the Pap test) is a medical procedure in which a sample of cells from a woman's cervix (the end of the uterus that extends into the vagina) is collected and spread (smeared) on a microscope slide. The cells are examined under a microscope in order to look for pre-malignant (before-cancer) or malignant (cancer) changes.

A Pap smear is a simple, quick, and relatively painless screening test. Its specificity - which means its ability to avoid classifying a normal smear as abnormal (a "false positive" result) - while very good, is not perfect. The sensitivity of a Pap smear - which means its ability to detect every single abnormality -- while good, is also not perfect, and some "false negative" results (in which abnormalities are present but not detected by the test) will occur. Thus, a few women develop cervical cancer despite having regular Pap screening.

In the vast majority of cases, a Pap test does identify minor cellular abnormalities before they have had a chance to become malignant and at a point when the condition is most easily treatable. The Pap smear is not intended to detect other forms of cancer such as those of the ovary, vagina, or uterus. Cancer of these organs may be discovered during the course of the gynecologic (pelvic) exam, which usually is done at the same time as the Pap smear.

Who should have a Pap smear?

Pregnancy does not prevent a woman from having a Pap smear. Pap smears can be safely done during pregnancy.

Pap smear testing is not indicated for women who have had a hysterectomy (with removal of the cervix) for benign conditions. Women who have had a hysterectomy in which the cervix is not removed, called subtotal hysterectomy, should continue screening following the same guidelines as women who have not had a hysterectomy.

The screening guidelines of several key medical organizations are summarized in the table below.

Organization	When to start Pap smear testing	Frequency of Pap smear testing	At what age to stop having Pap smears
American Cancer Society 2004	3 years after vaginal intercourse, no later than age 21	Yearly with exceptions: every 2 years if liquid-based kit every 2-3 years if three normal tests in a row in women >30 years old	Total hysterectomy for benign disease > 70 years old with at least three normal Pap smear results and no abnormal Pap results in the last 10 years
United States Preventative Services Task Force 2003	Within 3 years of onset of sexual activity or age 21, whichever comes first	At least every 3 years (no evidence that every year is better than every 3 years)	Recommend against doing Pap smears in women older than 65 years of age, if adequate screening with normal results and otherwise not at risk for cervical cancer. Recommend against doing Pap smears in women who have had a total hysterectomy for benign disease.
American College of Obstetrics and Gynecology	3 years after first sexual intercourse or age 21, whichever comes first.	Yearly until age 30 years. Beginning at age 30, if three normal annual Pap results, can do a Pap alone every 2-3 years	Difficult to set an upper age limit-postmenopausal women screened within the prior 2-3 years have a very low risk of developing abnormal Pap smears.