Since it came into use more than 50 years ago, the Pap test has greatly reduced the number of deaths caused by cervical cancer in the United States. The Pap test is used to find changes in the cells of the cervix that could lead to cancer. Once these changes are treated, cancer can be prevented.

The Cervix
The cervix is the lower, narrow end of a woman's uterus. It opens into the vagina (the birth canal). The cervix is covered by a thin layer of tissue. This tissue is like the skin inside your mouth.

What Is a Pap Test?
The Pap test, sometimes called a Pap smear or cervical cytology screening, is a simple test to look at cells taken from the cervix.

Who Should Have a Pap Test?
Pap tests are an important part of all women's health care. When and how often you have the test depends on your age and health history. You should have routine Pap tests if:

• You are 21 years of age or older or
• You became sexually active at least three years ago, even if you are younger than 21 years of age or are not having sex now

How Often Do You Need a Pap Test?
All women should have a pelvic exam yearly. When a woman has a pelvic exam with a speculum, a Pap test may or may not be done. Be sure you know if a Pap test has been included in your exam.

Talk with your doctor about whether and how often you should have a Pap test. Women younger than 30 years should have a Pap test every year. If you are older than 30 years and have had three normal Pap tests in a row, you may not need a Pap test every year.

The Test Results
Most labs in the United States use the "Bethesda System" to describe Pap test results. Under this system, your results will be placed in one of several groups:

• Normal (negative)
• Atypical squamous cells (ASC)
• SIL (squamous intraepithelial lesion)
  • Low-grade SIL (LSIL)
  • High-grade SIL (HSIL)
• Atypical glandular cells
• Cancer

Follow-Up
Cells taken from the surface of the cervix sometimes look abnormal. Usually abnormal cells are not cancer. Abnormal cells may go through many stages of change before cervical cancer appears. This often happens over a number of years.

If the lab finds abnormal cells, your doctor may suggest more tests. This may be as simple as a repeat Pap test.

Your doctor also may want to test for human papillomavirus (HPV). HPV is a group of related viruses, a few of which are linked to cervical changes.

Sometimes an exam called a colposcopy may be advised. This exam uses a device like a microscope to look at the cervix.

If an area of abnormal cells is seen, your doctor may decide that a cervical biopsy is needed.

Treatment depends on the test results.

Is the Pap Test Always Accurate?
As with any lab test, Pap test results are not always accurate. Sometimes, the results show abnormal cells when the cells are normal. This is called a "false-positive" result. A Pap test also may fail to detect abnormal cells when they are present. This is called a "false-negative" result.

Finally ...
The Pap test is the best way to find cell changes that may lead to cancer of the cervix. Routine Pap tests can help find problems early. If a Pap test finds abnormal cells, your doctor will suggest further tests or treatment.