The Pap test is used to screen women for cancer of the cervix. Named for the doctor who designed the test (George Papanicolaou), the Pap test is very reliable for detecting early abnormal cell changes that could lead to cancer. In the United States, the use of the Pap test as a screening tool for cervical cancer has dramatically increased cure rates. Regular Pap tests are recommended for women between the ages of 18 and 65.

During a Pap test, a small sample of cells from the surface of the cervix is collected by a health professional. The sample is then spread or smeared on a slide (Pap smear) and sent to a lab for examination under a microscope. The cells are examined for abnormalities that may indicate cancer or changes that could lead to cancer.

Cervical cancer is one of the most common types of cancer affecting women. It is also one of the few cancers with well-defined stages. Chances of a cure are higher when it is detected before it has spread from the cervix to other parts of the body.

Several factors increase a woman's risk of developing cervical cell changes that can lead to cancer of the cervix. These risk factors include:

• A personal history of precancerous changes of the cervix or cervical cancer.
• Being infected with certain types of the human papillomavirus (HPV).
• A previous abnormal Pap test.
• Starting sexual intercourse at an early age (younger than 18 years old).
• Having three or more sex partners in a lifetime.
• Having a weakened immune system.

Pap Test
Results

Results from a Pap test are usually available in 1 to 2 weeks.

Normal

The sample of cells collected from the cervix is adequate (cells from the surface of the cervix and inside the cervix are present) and no abnormal cells are detected.

Abnormal

In the United States, abnormal cells are classified using the Bethesda system (TBS), which is becoming the accepted standard. The Bethesda system provides more information about the cell sample than the CIN (cervical intraepithelial neoplasia) system, an older system of classification.

The Bethesda system (TBS)

The Bethesda system of reporting Pap test results consists of three parts. A fourth part can be used to describe changes in cells from the vagina.

Part I: Sample suitability

The quality of the cell sample may be described as:

1. Satisfactory for evaluation.
2. Satisfactory for evaluation, but limited by some factor that may affect the exam (such as blood on the slide or signs of an infection).
3. Unsatisfactory for evaluation (for which a reason will be given, such as too few cells collected).

Part II: General categorization (optional)

One of three statements is chosen to indicate if the cells collected were normal or abnormal. This information is optional and may not be reported. The cells may be described as:

1. Within normal limits.
2. Noncancerous (benign) cell changes. This is explained further by using one of the specific diagnoses from Part III.
3. Surface cell abnormality. This is explained further by using one of the specific diagnoses from Part III.

Part III: Descriptive diagnosis

Abnormal cell changes are described as:

1. Noncancerous (benign) cell changes, which can be caused by:
   • Infection (for example, yeast infections or sexually transmitted diseases such as chlamydia, trichomoniasis, or genital herpes). This category does not include cell changes due to certain types of the human papillomavirus (HPV).
   • Changes (such as inflammation) from normal repair processes of the cervical cells or other causes (such as changes caused by an intrauterine device or exposure to radiation).
2. Surface cell abnormalities, which can be classified as:
   • ASCUS. This category is used for minor cell changes due to unknown causes. A judgment is made by the laboratory doctor (pathologist) as to whether the changes are likely to progress to a more serious condition.
   • LSIL. This category is used for cells that show definite minor changes but are unlikely to progress to cancer. This category includes cervical cell changes due to certain types of the human papillomavirus (HPV).
   • HSIL. This category is used for cell changes that have a high likelihood of progressing to cancer or are in the early stages of cancer.
   • Cervical cancer. Cancer of the cervix is suspected.
   • Endometrial cells. This category is used to describe cells from the lining of the uterus (endometrial cells) that have moved to the cervix. This may be an abnormal condition. The endometrial cells are not cancerous but may indicate another problem (such as endometriosis).
   • Atypical Glandular Cells of Undetermined Significance (AGUS). This category is used when abnormal gland cells were found on a Pap smear, but the reason for the abnormalities is not known. A judgment is made as to whether the condition is likely to progress to a more serious condition.
   • Glandular cancer. Cancer arising from cervical glandular cells.
   • Endometrial cancer. Cancer arising from cells that line the uterus (endometrial cells).
   • Other types of cancer. Cancer that has spread to the cervix from elsewhere in the body.
   • Other types of glandular cell cancer. Glandular cell cancer that has spread to the cervix from elsewhere in the body.

Part IV: Vaginal cells changes

The Bethesda system may include a fourth part that describes changes in cells from the vagina. One of three statements is chosen to describe the findings.

1. Findings are normal for the woman's age and medical history.
2. Findings are abnormal for the woman's age and medical history. The specific reason for this is provided.
3. An evaluation was not possible. The specific reason for this is provided.

The CIN (cervical intraepithelial neoplasia) system

Changes in cells on the surface of the cervix can be called cervical intraepithelial neoplasia (CIN). CIN is not cancer. It is a condition where normal cells show some change. Untreated CIN may progress to cancer of the cervix.

The CIN system classifies abnormal Pap tests by a number.

• CIN 1. Mildly abnormal cell changes. This corresponds to the ASCUS or LSIL category of the Bethesda system.
• CIN 2. Moderately abnormal cell changes. This corresponds to the HSIL category of the Bethesda system.
• CIN 3. Severely abnormal cell changes. These are the most severe cell changes that are not yet cancerous. This corresponds to the HSIL category of the Bethesda system.