Pap Test

Definition

The Papanicolaou (Pap) test involves scraping cells from the cervix (the lower narrow portion of the uterus that connects to the vagina) and examining them under a microscope for signs of cervical cancer or abnormal cells that could lead to cancer .

Purpose

Pap tests, also referred to as cervical smears or cervical/vaginal cytology, can detect abnormal cervical cells before they develop into cancer cells. Pap tests also detect cervical cancer in its early stages when it is easier to treat, as well as noncancerous conditions such as infection and inflammation. Most cases of invasive cervical cancer can be prevented by regular Pap tests. Since 1950 new cases of and deaths from cervical cancer have declined sharply due to widespread screening with the Pap test. Deaths from cervical cancer are as of 2008 rare in women of any age who have regular Pap tests. Of American women diagnosed with cervical cancer, 60% had not had a Pap test in the previous five years.

Almost all cervical cancers are caused by persistent infection with the human papillomavirus (HPV), which is spread through sexual contact. However, temporary

HPV infections and insignificant cervical cell changes are very common, and it takes years for significant abnormalities or cancer to develop. Therefore, Pap tests should be performed at least once every three years, starting about three years after a woman begins having sexual intercourse but no later than age 21.

If Pap tests between the ages of 55 and 65 are normal, women are often advised that no further screening is necessary. Women who have a negative Pap test at age 60 or older are very unlikely to have a subsequent abnormal Pap. Women aged 65 and over who have never had a Pap test are advised to have two tests one year apart: if both tests are normal, no further testing is necessary.

Pap tests are not useful in women who have had a total hysterectomy in which the uterus and cervix were removed unless the surgery was for cervical pre-cancer or cancer. These women should be tested annually for vaginal cancer until they have had three normal test results.

Precautions

Pap tests miss up to 20% of cervical cell abnormalities. Such false-negative results may delay treatment even in the presence of symptoms of cervical cancer. However, since changes in cervical cells occur very slowly, abnormalities should be detected in a subsequent Pap test within the next three years.

False-positive results occur when cells appear abnormal although no cancer is present. Some abnormal cervical cells never become cancerous. False-positive results can cause anxiety and lead to more tests and procedures which have their own risks.

Description

Pap tests are performed in doctors' offices, clinics, local health departments, and hospitals, usually in the course of a pelvic examination. The woman lies on an exam table with a sheet over her legs and stomach, her feet in holders called stirrups, and her knees open. A female staffer is always present. A plastic or metal instrument called a speculum is used to widen the vagina so that the upper part of the vagina and cervix are visible. Cells are scraped from the surface of the cervix and vagina using a piece of cotton, a small cervical brush, or a small wooden scraper or stick.

The cells are placed on a microscope slide, treated with fixative, and sent to a laboratory. The cells are examined under a microscope to look for abnormalities. With a new liquid-based, thin-layer slide preparation, the brush or other collection device is rinsed in a vial of liquid preservative and the vial is sent to the lab where an automated device prepares the slide. This eliminates background material and provides a thin layer of cells for analysis. Studies suggest that this procedure is more sensitive than the traditional Pap smear. Computer-automated readers can send the image to a computer for analysis. Sometimes an HPV DNA test to detect strains of HPV associated with cervical cancer is performed at the same time as the Pap test.

Preparation

Pap tests should not be performed during menstruation. The best time for a Pap test is 10 to 20 days after the first day of the last menstrual period. Women should avoid douching or using vaginal medicines or deodorants, spermicidal foams, creams, or jellies, or tampons for about two days before a Pap test since these products can disguise or wash away abnormal

cells. Women should avoid sexual intercourse for 48 hours before a Pap test to avoid inconclusive results that may require retesting.

Aftercare

Following a Pap test a woman may immediately resume her normal activities.

Complications

Some Pap tests are unreadable and need to be repeated due to the following:

• too few cells in the specimen
• clumped cells
• obscuring by blood or mucus.

Results

Lab reports

Pap-test results come back from the laboratory in one to two weeks. Most U.S. laboratories use the Bethesda System for reporting Pap-test results:

• “Negative for intraepithelial lesion or malignancy” is a normal result meaning that no abnormal cells were found on the surface of the cervix.
• Atypical squamous cells of undetermined significance (ASC-US) indicates that the squamous cells—the flat thin cells that line the surface of the cervix—do not appear completely normal, perhaps due to HPV infection, but the significance of the abnormality is unknown.
• Atypical squamous cells-H (ASC-H) indicates that the cells are atypical, and although the significance is unclear, a precancerous high-grade squamous intraepithelial lesion (SIL) cannot be excluded.
• Atypical glandular cells (AGC) indicates that the mucus-producing cells in the endocervical canal (the opening at the center of the cervix) or in the lining of the uterus do not appear normal, but the significance of the change is unclear.
• Endocervical adenocarcinoma-in-situ (AIS) means that precancerous cells are found in the glandular or mucus-producing tissue.
• Low-grade squamous intraepithelial lesion (LSIL) indicates early changes in the size and shape of the squamous cells caused by HPV infection.
• High-grade squamous intraepithelial lesion (HSIL) indicates markedly abnormal or precancerous cells with a higher probability of progressing to invasive cervical cancer.
• Cancer cells are present.

Healthcare providers may use slightly different terms to describe abnormal Pap-test results:

• Dysplasia indicates the presence of abnormal cells which could develop into very early cervical cancer. It is categorized as mild, moderate, severe, or carcinoma-in-situ (CIS) (cancer cells confined to the surface of the cervix) depending on the degree of abnormality; mild dysplasia is a LSIL and moderate to severe dysplasia or CIS is an HSIL.
• Cervical intraepithelial neoplasia (CIN) indicates abnormal growth of cells on the surface of the cervix. It is categorized as CIN-1 to 3 depending on the severity; CIN-1 is equivalent to a LSIL or mild dysplasia; CIN-2 and -3 are HSIL, moderate to severe dysplasia, or CIS.
• Cervical cancer indicates that cancer cells have spread deeper into the cervix.
• Invasive cervical cancer means that cancer cells have spread to other tissues or organs.

Follow-up

Cervical cells can undergo changes for many reasons other than cancer, including the following:

• inflammation
• bacterial, viral, or yeast infection
• growths such as benign polyps or cysts
• hormone changes due to pregnancy or menopause.

Of about 55 million Pap tests performed annually in the United States, about 3.5 million or 6% are abnormal and require medical follow-up. The Pap test may be repeated, particularly if the results are ambiguous or indicate only a minor abnormality, since abnormal cervical cells often disappear without treatment. Cell changes are often caused by low hormone levels. An ACS-US result in a woman who is near or past menopause can often be cleared up with the application of an estrogen cream to the cervical surface for a few weeks. Following two normal Pap results women can return to routine Pap tests every three years.

ASC-US, ASC-H, LSIL, or HSIL Pap results are often followed by colposcopy, in which the cervix is coated with a dilute vinegar solution that turns abnormal cells white and a lighted magnifying instrument called a colposcope is used to examine the vagina and cervix.

An HPV DNA test may be performed to determine whether the abnormal cells are the result of infection with an HPV that is linked to cervical cancer. A large clinical trial has indicated that testing a cervical sample for HPV is more efficient than colposcopy or a repeat Pap test for identifying ASC-US abnormalities that require treatment. It was expected as of 2008 that HPV tests may replace Pap tests for routine cervical cancer screening.

QUESTIONS TO ASK YOUR DOCTOR

• How often should I have a Pap test?
• Now that I am 60 do I still need to have Pap tests?
• Should I be tested for HPV?
• When will I learn the results of my Pap test?
• What do my Pap-test results mean?
• What will the treatment be?
• Should I have another Pap test or get a second opinion?

If colposcopy reveals abnormal cells, the cervix may be examined with a LUMA Cervical Imaging System, which shines a light on the cervix. Normal and abnormal cells respond differently to the light and the system produces a colored map that distinguishes between them.

If these procedures indicate the presence of cells that may be precancerous, various additional tests and procedures may be utilized to diagnose and treat the condition.

Care team concerns

Pap tests are performed by the following:

• physicians
• physician assistants
• nurse-midwives
• nurse practitioners
• women's healthcare specialists.

A pathologist supervises the examination of the Pap smear for abnormalities.

Resources

BOOKS

Comprehensive Cervical Cancer Control: A Guide to Essential Practice. Geneva: World Health Organization, 2006.

Hoda, Rana S., and Syed A. Hoda. Fundamentals of PAP Test Cytology. Totowa, NJ: Humana Press, 2007.

Rushing, Lynda, and Nancy Joste. Abnormal Pap Smears: What Every Woman Needs to Know. Amherst, NY: Prometheus, 2008.

Sutton, Amy L. Cancer Sourcebook for Women, 3rd ed. Detroit: Omnigraphics, 2006.

KEY TERMS

AGC —Atypical glandular cells; a Pap-test result indicating that mucus-producing cells in the cervix or lining of the uterus appear abnormal.

AIS —Endocervical adenocarcinoma-in-situ; a Pap test result indicating precancerous cells in the glandular or mucus-producing tissue of the cervix.

ASC-H —Atypical squamous cells; a Pap-test finding of atypical cells of unknown significance with the possibility of a precancerous high-grade squamous intraepithelial lesion.

ASC-US —Atypical squamous cells of undetermined significance; a Pap-test result.

Carcinoma-in-situ (CIS) —Cancer cells confined to the surface of the cervix.

Cervix —The lower narrow part of the uterus that opens to the vagina.

CIN —Cervical intraepithelial neoplasia; abnormal growth of cells on the surface of the cervix.

Colposcopy —The use of a magnifying instrument to examine the vagina and cervix.

Dysplasia —Growth of abnormal cells.

Endocervical canal —The opening at the center of the cervix.

HPV —Human papillomavirus, some strains of which cause warts and others can cause cervical cancer.

HSIL —High-grade squamous intraepithelial lesion; moderate to severe dysplasia; a Pap-test finding of abnormal or precancerous cells with a higher probability of progressing to invasive cervical cancer.

Intraepithelial —On the surface of the cervix.

Lesion —Abnormal cells.

LSIL —Low-grade squamous intraepithelial lesion; mild dysplasia; a Pap-test finding of early changes in the size and shape of squamous cells.

Neoplasia —Tumor formation.

SIL —Squamous intraepithelial lesion; abnormal squamous cells on the surface of the cervix.

Speculum —An instrument used to widen the vagina so that a Pap test can be performed.

Squamous —Small scale-like cells on the surface of the cervix.

PERIODICALS

Runowicz, C. D. “Molecular Screening for Cervical Cancer—Time to Give Up Pap Tests?” New England Journal of Medicine 357, no. 16 (October 16, 2007):1650–1653.

Sirovich, Brenda E., et al. “Screening for Cervical Cancer: Will Women Accept Less?” American Journal of Medicine 118, no. 2 (February 2005): 151.

OTHER

“Cervical Cancer Screening.” National Cancer Institute December 19, 2007 [cited March 3, 2008]. http://www.cancer.gov/cancertopics/pdq/screening/cervical/Patient/page1.

“Pap Smear.” Lab Tests Online March 23, 2005 [cited March 4, 2008]. http://www.labtestsonline.org/understanding/analytes/pap/glance.html.

“Pap Test.” The National Women's Health Information Center March 2006 [cited March 4, 2008]. http://womenshealth.gov/faq/pap.htm.

“The Pap Test: Questions and Answers.” National Cancer Institute March 29, 2007 [cited March 4, 2008]. http://www.cancer.gov/cancertopics/factsheet/Detection/Pap-test.

ORGANIZATIONS

National Breast and Cervical Cancer Early Detection Program, Centers for Disease Control and Prevention, Division of Cancer Prevention and Control, 4770 Buford Hwy. NE, MS K-64, Atlanta, GA, 30341-3717, (800) CDC-INFO, (770) 488-4760, [email protected], http://www.cdc.gov/cancer/NBCCEDP/about.htm.

National Cancer Institute, NCI Public Inquiries Office, 6116 Executive Blvd., Room 3036A, Bethesda, MD, 20892 8322, (800) 4-CANCER, http://www.cancer.gov.

Planned Parenthood Federation of America, 434 West Thirty-third Street, New York, NY, 10001, (212) 541-7800, (800) 230-7526, (212) 245-1845, http://www.ppfa.org.

Margaret Alic Ph.D.