A Pap smear, also known as a Pap test, is a procedure that collects cells from the cervix, (lower, narrow end of the uterus). Laboratory analysis of the sample is used to detect any abnormalities that might suggest the presence of infection, inflammation or cervical cancer. The American Cancer Society (ACS) recommends that women have their first Pap smear three years after first having sexual relations, or at age 21 if they have not been sexually active. Other experts suggest these tests should begin no later than age 18.

Dr. George Papanicolaou developed the Pap smear more than 60 years ago, and it is now a standard gynecological screening test. As a result, the rate of death from cervical cancer has dropped dramatically over the years. Women who have regular Pap smears are unlikely to develop invasive cervical cancer as the test is effective in detecting precancerous conditions. In addition, it allows for the disease to be detected in its early stages when the cervical cancer is highly treatable.

Each year, 55 million Pap tests are performed in the United States, according to the National Cancer Institute (NCI). Approximately 6 percent – or 3.5 million – are found to be abnormal and require some form of medical follow-up.

A Pap smear is a test that is used to detect abnormal cells on the cervix. An abnormal Pap smear result is often is the first indicator of the presence infection, inflammation or cervical cancer. If the Pap smear indicates the presence of abnormalities, follow-up testing will be necessary to diagnose the precancer or cancerous condition.

Since the Pap smear was developed by Dr. George Papanicolaou more than 60 years ago, the rate of death from cervical cancer has dropped dramatically. Women who have regular Pap smears are unlikely to develop an invasive form of this disease. The Pap smear is effective for diagnosing precancerous changes or cervical cancer in its early stages. When cervical cancer is detected early, it is highly treatable with an improved success rate.

Each year, 55 million Pap tests are performed in the United States, according to the National Cancer Institute. Approximately 6 percent of these show abnormal results that require medical follow-up.

The American Cancer Society (ACS) recommends that women have their first Pap smear three years after first having sexual relations, or at age 21 whichever occurs first. Other experts suggest these tests should begin no later than age 18.

After the age of 21 years, the ACS recommends the following schedule:

Women with certain risk factors may need to be screened annually or on a more frequent schedule if recommended by their physician. These women may have the following lifestyle risk factors:

• History of sexual activity as a teen, especially if there is a history of more than one sexual partner.
  
  
• Multiple sex partners at present.
  
  
• Partner who began sexual activity at an early age or who had many previous sexual partners.
  
  
• Infection with the human papillomavirus (HPV), the virus that can cause genital warts. Although the types of HPV that cause genital warts (e.g., HPV types 6 and 11) are considered low risk for precancerous cervical changes, infection with certain high-risk forms of the virus (e.g., HPV types 16 and 18) are a major cause of cervical cancer and are also associated with other genital cancers including vulvular and anal.
  
  
• History of other sexually transmitted diseases (e.g., herpes, chlamydia).
  
  
• Tobacco use.

Other factors that may warrant an annual or more frequent Pap smear include:

• Family history of cervical cancer.
  
  
• Diagnosis of cervical cancer or previous precancerous Pap smear.
  
  
• Exposure to DES (diethylstilbestrol) before birth. DES is a potent synthetic estrogen that was used from 1940 to 1970.
  
  
• Weakened immune system due to chronic illness (e.g., HIV/AIDS), organ transplant, chemotherapy treatment or prolonged corticosteroid use.

A Pap smear is typically conducted as part of a woman’s pelvic examination during a regular gynecological visit. Pelvic exams include examination of the uterus, vagina, ovaries, fallopian tubes, bladder and rectum.

Women who have had a total hysterectomy (surgical removal of the uterus and cervix) should ask a physician whether they need to continue to have Pap smears. In many cases, women who have had hysterectomies performed for noncancerous reasons – such as uterine fibroids – may be allowed to skip Pap smears as long as they continue to have regular pelvic examinations. However, in cases where the results indicate cervical malignancies, a Pap test will be used to screen for vaginal or vulva abnormalities that could indicate a recurrence. In these situations, a yearly Pap test will likely be recommended.

Women should follow all of the preparatory steps recommended by their physician. In addition, they should:

• Avoid sexual intercourse for two days prior to the test.
  
  
• Avoid douching or using any vaginal medicines or spermicidal foams, creams or jellies for two days before the Pap smear. These may wash away or obscure abnormal cells.
  
  
• Try not to schedule a Pap smear during a menstrual period. The best time for a Pap smear is 10 to 20 days after the first day of the last menstrual period.

Pap smears are usually performed as part of a woman’s regular pelvic exam, which will also include an examination of the external genitals, uterus, ovaries, other reproductive organs and the rectum.

A Pap smear is performed in just a few minutes in a physician’s office. The patient will usually be asked to remove her clothing and change into a hospital gown. The patient then lies down on an examination table with her knees bent and to the sides, and heels resting in supports called stirrups. A sheet covers the woman’s legs and stomach. The physician (or physician assistant, nurse-midwife or nurse practitioner) gently inserts an instrument called a speculum into the woman’s vagina to widen it and cleans the cervix with a cotton swab. The swab, a small brush or a tiny spatula are used to obtain a sample of cells from the cervix. The cells are then smeared onto a glass slide for examination in a laboratory.

A newer approach to cell transfer has the physician obtain the cell sample before rinsing the instruments in a special liquid that preserves the cells for examination. The specimen is then filtered in a machine that reduces the amount of blood and mucus (thin prep). This can help make the sample easier to interpret.

A Pap smear is generally painless, although some women report minor discomfort during the procedure.

It can take up to several weeks to receive test results from a Pap smear. The cell sample will be sent to a laboratory for analysis by a cytotechnologist, who is trained to detect abnormal cells. The cytotechnologist works with a physician known as a pathologist (expert in cellular abnormalities) to examine the cells under a microscope. The pathologist then makes a diagnosis as to the status of the cells (e.g. normal, precancerous, cancerous).

If the cell sample has been preserved using the newer liquid technique, a technician at the laboratory will be able to prepare a slide that is cleaner and easier to interpret than a traditional sample. In addition, new computer–automated readers are being used to analyze Pap smears. The technology uses a microscope that feeds an image to a computer. The image is then analyzed for the presence of abnormal cells.

The potential findings of a Pap smear are classified according to the Bethesda System, and include:

• Normal. The test is negative, and no abnormal cells are found. No further treatment will be necessary until the next pelvic examination.
  
  
• Atypical squamous cells (ASC). Squamous cells are the thin, flat cells that grow on the cervix’s surface. This diagnosis indicates the presence of slightly abnormal cells that might be the result of infection, inflammation or a precancerous condition (cervical dysplasia). A second Pap smear or another test may be performed to help pinpoint the cause of the abnormal cells.
  

  

• Atypical glandular cells (AGC). Glandular cells produce mucus and grow in the center of the opening of the cervix and within the lining of the uterus. Further testing is necessary to determine whether the cells are cancerous.
  
  
• Endocervical adenocarcinoma in situ (AIS). Cells that are likely precancerous and are found in the glandular tissue. Patients with endocervical AIS may require additional diagnostic testing.
  
  
• Squamous intraepithelial lesion (SIL). Indicates that the cells seen on the Pap smear are consistent with cervical dysplasia, a precancerous condition. Diagnostic testing is likely after such a result. Low-grade squamous intraepithelial lesion indicates early changes that are considered to be mild abnormalities. High-grade squamous intraepithelial lesion indicates more pronounced changes in the size and shape of the abnormal cells, and a greater likelihood of cervical cancer. 

A negative result means that abnormal cells were not found. A positive result means that abnormal cells were found, but does not necessarily indicate cancer. The only way to confirm a diagnosis is to remove a sample of tissue (biopsy) and send it to a laboratory for analysis.

In addition to cancer, abnormal cells may be the result of inflammation caused by infection with the human papillomavirus (HPV), herpes virus, yeast infection or other infections.

In some cases, Pap smears may produce a false positive (incorrectly indicating a problem) or false negative (failing to indicate a problem). False negative tests may occur up to 20 percent of the time, but false positives are extremely rare. False negatives can be caused by many factors, including:

• Inadequate collection of cells
• Small number of abnormal cells
• Inaccessible location of the lesion
• Small size of the lesion
• Abnormal cells mimicking benign cells
• Blood or inflammatory cells obscuring the abnormal cells

Although abnormal cells sometimes go undetected, they are often caught in future screenings, as cervical cancer takes years to develop.

In many cases, abnormal cells changes in the cervix resolve without any treatment. In other cases, some form of follow–up diagnosis or treatment may be necessary. These include:

• Colposcopy exam. An instrument resembling a microscope called a colposcope may be used to examine the vagina and cervix. During the examination, a dilute vinegar solution may be applied to the cervix. Abnormal areas will turn white and under magnification blood vessels and cells acquire certain characteristics as they become abnormal. The physician may also perform a biopsy of these abnormal areas during this procedure.
  
  
• Imaging test. Immediately following a colposcopy exam, physicians may now use a new imaging device to determine whether there are other areas of the cervix that need to be biopsied. Approved by the Food and Drug Administration in March 2006, the LUMA Cervical Imaging System shines a light on the cervix and analyzes how the areas of the cervix respond to the light. Based on the response, the LUMA system assigns a score to small areas of the cervix and produces a color map of the surface. The score and color map can help physicians distinguish between healthy tissue and potentially cancerous tissue. With the score and color map, physicians can determine where to perform biopsies on the cervix. It should be noted that the LUMA system is meant to supplement – and not replace – the colposcopy exam. Physicians will perform the cervical biopsies only after reviewing the information from both the colposcopy and LUMA exams.
  
  
• Estrogen cream. Women who have atypical squamous cells (ASC) and are in or near menopause may be experiencing cell changes as a result of low hormone levels. These women may be given an estrogen cream to see if this reverses the abnormalities.
  
  
• Endocervical curettage. A procedure in which the mucous membrane of the cervical canal is scraped using a spoon–shaped instrument called a curette. The sample that is obtained is sent to a laboratory for analysis. In the event of an abnormality, this analysis will determine if it has spread beyond the cervix.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor or healthcare professional the following questions about Pap smears:

1. At what age should I start getting a Pap smear, and how often?
   
   
2. What preparatory steps I should follow before the test?
   
   
3. How does the liquid Pap test differ from the standard one? Which one is best for me?
   
   
4. When will I receive the results of the test and by whom?
   
   
5. What does an abnormal result mean?
   
   
6. Will I need a repeat Pap smear if the test is positive?
   
   
7. What follow-up tests might I need?
   
   
8. Will I need treatment if my Pap test is abnormal?
   
   
9. How will you determine if my condition indicates cancer?
   
   
10. If I have an abnormal Pap test, am I at risk for cervical cancer in the future?
    
    
11. At what age should I stop receiving Pap tests?