The PAP Smear

The PAP smear is a screening test for detecting cancerous or precancerous changes of the cervix. The test was developed by Dr. George Papanicolaou in the 1940’s. Since its introduction over 50 years ago, a woman’s chance of dying from cancer of the cervix has decreased by over 75%. This makes the PAP smear one of the most effective cancer screening tests ever invented.

The cervix is the opening of the uterus (or womb). It is covered with a thin layer of tissue that is similar to skin; and just like the skin on your body, the cells that make up this tissue are constantly being shed to make room for the newer, healthier cells. It is these cells which have shed that are collected during the PAP smear, and viewed under a microscope for abnormalities.

Since 1988, the American College of Obstetricians and Gynecologists, and several other health organizations have recommended that all women who are sexually active or who have reached the age of 18 years old (whichever comes first) should have an annual PAP smear and pelvic exam. After a woman has had three or more consecutive normal PAP’s, this time interval could be extended at the discretion of her physician. However, the interval should probably never exceed 3 years.

It is important to remember that although the PAP is a screening test for cancer of the cervix, cancer is not usually the cause of most abnormal smears. Before cervical cancer develops, there are usually several stages of abnormal cells called "dysplasia" (also known as "cervical intraepithelial neoplasia" or CIN). CIN changes take several years to develop and progress, which is why the PAP smear is so effective. When these abnormal cells are found, they can often be treated with procedures in your doctor’s office which avoids hospitalization. Keep in mind that like any screening test, 10-20% of the time, a normal PAP result could be a "false-negative". This means that a normal result is reported even though abnormal cells are present. This reinforces the need for yearly PAP smears, which in the long run will cut down on the false-negative results.

Some women are at a higher risk for developing abnormal cervical changes. This group includes those who are smokers, those who began having intercourse at an early age or have had more than one sexual partner. Also included are women who have had genital warts caused by the human papillomavirus (HPV), and those who are infected with human immunodeficiency virus (HIV).

If you have an abnormal PAP smear result, don’t panic. There is very low probability of finding invasive cancer, in fact most of the time only dysplasia (CIN), or nothing at all will be found. Your doctor will recommend what further action needs to be taken. Usually this will either be a repeat of the PAP smear in several months, or a colposcopy. Colposcopy means that your doctor will use an in-office magnification system to closely inspect your cervix, and possibly to take a biopsy. If at any point in this process you are uncertain about the nature of your treatment, please discuss it further with your physician.

References:

Bibliography

1. Novak’s Gynecology, Twelfth Edition, Jonathan S. Berek, MD, Williams &Wilkins, Baltimore, 1996.

2. Low-Grade Papanicolaou Smears And The Bethesda System: A Prospective Cytohistopathologic Analysis, Lonky, N.M., Obstet Gynec, Vol. 85, No. 5, Pt. 1, May 1995.

3. The PAP Test, ACOG Patient Education, Special Procedures, AP085.

4. Cervical Cytology: Evaluation and Management of Abnormalities, ACOG Technical Bulletin #183, August 1993.

5. Genital Human Papillomavirus Infections, ACOG Technical Bulletin #193, June 1994.

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