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A Pap smear is a sampling of cells from a woman's cervix. The cervix is the opening between the vagina and the uterus. The cells are scraped from the cervix during a pelvic exam.

Cervical dysplasia is a condition, caused by infection with certain strains of the human papillomavirus (HPV), in which a woman has abnormal changes in the top layer of cells of her cervix. These changes are an early sign that cervical cancer may develop. A cervical cell goes through precancerous stages for months to years before becoming an invasive, malignant, carcinoma.

Catching the disease at the precancerous stage can prevent the development of cervical cancer. Since the Pap smear was introduced 60 years ago, deaths from cancer of the cervix have decreased by 70%.

Who is a candidate for the test?

The American Cancer Society recommends that women have yearly Pap smears beginning by age 21 or when they have been sexually active for three years or more. If a woman over age 30 has had three negative annual Pap tests in a row, the healthcare professional may recommend less frequent testing. Some women may need more frequent screenings if they are at high risk for cancer of the cervix.

Risk factors include the following:

• becoming sexually active before age 18
• having three or more sexual partners, or having sex with a partner who has had many partners
• having sex with an uncircumcised male
• having a sexual partner who has or has had cancer of the penis
• having a sexual partner whose previous partner had cancer of the cervix or cervical dysplasia
• having a weakened immune system, for example, due to HIV or other immunodeficiency disorder
• having had a previous diagnosis of human papillomavirus infection
• having had a previous abnormal Pap smear
• having had cancer of the vagina or vulva
• a history of cancer of the cervix in a woman's sister or mother
• not using condoms with new sexual partners
• smoking

How is the test performed?

The first step is for the healthcare professional to perform a pelvic exam. A speculum is a metal or plastic instrument that is placed in the vagina. This instrument allows the examiner to see the interior of the vagina and the cervix.

A small, sterile brush is used to take a sample of cells from the internal opening of the cervix. A small wooden spatula is used to scrape the outside of the cervix. These two scrapings are placed on a glass slide or in a small bottle filled with a special liquid. The cells are analyzed later under a microscope in a laboratory.

What is involved in preparation for the test?

A Pap smear should be performed at least five days after the end of the last menstrual period. Women should not douche or have sexual intercourse for 24 hours before the test. No vaginal creams, diaphragms, or tampons should be used for 24 hours before the test. To minimize discomfort, a woman should empty her bladder just before the exam.

What do the test results mean?

A healthy Pap smear shows no abnormal cells or evidence of inflammation. The presence of abnormally growing cells on the surface of the cervix may be reported as an abnormal PAP smear.

Categories of cell changes include:

• ASCUS (atypical squamous cells of undetermined significance)
• AGUS (atypical glandular cells of undetermined significance)
• LSIL (low grade squamous intraepithelial lesion-possible HPV or CIN I)
• CIN I (mild dysplasia)
• CIN II (moderate dysplasia)
• HSIL (high grade squamous lesions, CIN II, CIN III, CIS)
• CIN III (severe dysplasia)
• CIS (carcinoma in situ)

All of these categories describe different degrees of abnormal cells. Not all mean that a woman has or will develop cervical cancer. However, a woman should follow up with her healthcare professional if her Pap smear results are abnormal. All these changes are within the top layer of the cervix. The cancer has not spread more deeply into the cervix or to other organs.

A woman who has had two or more abnormal Pap smears (ASCUS, CIN I, or HPV changes), or one Pap smear with a higher degree of abnormality, should undergo colposcopy. This is a test in which the cervix is viewed with a special lighted microscope. A cervical biopsy may also be needed. This involves taking a small tissue sample from the cervix. The sample is examined further to find the cause of the abnormal cells.