The Pap (Papanicolaou) Test

The Pap test is a procedure used to collect cells from the cervix so that they can be looked at under the microscope to find cancer and pre-cancer.

How the Pap test is done

The Pap test is a procedure used to collect cells from the cervix so that they can be looked at under the microscope to find cancer and pre-cancer.

The health care professional first places a speculum inside the vagina. The speculum is a metal or plastic instrument that keeps the vagina open so that the cervix can be seen clearly. Next, using a small spatula, a sample of cells and mucus is lightly scraped from the exocervix. A small brush or a cotton-tipped swab is then inserted into the opening of the cervix to take a sample from the endocervix (see illustration in   What is cervical cancer?  section). If your cervix has been removed (because you had a trachelectomy or hysterectomy) as a part of the treatment for a cervical cancer or pre-cancer, the cells will be sampled from the upper part of the vagina (known as the  vaginal cuff ). The samples are then prepared so that they can be looked at under a microscope in the lab.

Although the Pap test has been more successful than any other screening test in preventing a cancer, it’s not perfect. One of the limitations of the Pap test is that the results need to be examined by the human eye, so an accurate analysis of the hundreds of thousands of cells in each sample is not always possible. Engineers, scientists, and doctors are working together to improve this test. Because some abnormalities may be missed (even when samples are looked at in the best labs), it’s not a good idea to have this test less often than American Cancer Society guidelines recommend.

Making your Pap tests more accurate

You can do several things to make your Pap test as accurate as possible:

• Try not to schedule an appointment for a time during your menstrual period. The best time is at least 5 days after your menstrual period stops.
• Don’t use tampons, birth-control foams or jellies, other vaginal creams, moisturizers, or lubricants, or vaginal medicines for 2 to 3 days before the Pap test.
• Don’t douche for 2 to 3 days before the Pap test.
• Don’t have vaginal sex for 2 days before the Pap test.

A pelvic exam is not the same as a Pap test

Many people confuse pelvic exams with Pap tests. The pelvic exam is part of a woman’s routine health care. During a pelvic exam, the doctor looks at and feels the reproductive organs, including the uterus and the ovaries and may do tests for sexually transmitted disease. Pelvic exams may help find other types of cancers and reproductive problems. Pap tests are often done during pelvic exams after the speculum is placed. Sometimes a pelvic exam is done without having a Pap test, but a Pap test is needed to find early cervical cancer or pre-cancers. Ask your doctor if you had a Pap test with your pelvic exam.

How Pap test results are reported

The most widely used system for describing Pap test results is the Bethesda System (TBS). There are 3 main categories, some of which have sub-categories:

• Negative for intraepithelial lesion or malignancy
• Epithelial cell abnormalities
• Other malignant neoplasms.

You may need further testing if your Pap test showed any of the abnormalities below. See Work-up of abnormal Pap test results.

Negative for intraepithelial lesion or malignancy

This category means that no signs of cancer, pre-cancer, or other significant abnormalities were found. There may be findings that are unrelated to cervical cancer, such as signs of infection with yeast, herpes, or Trichomonas vaginalis (a microscopic parasite), for example. Specimens from some women may also show “reactive cellular changes”, which is the way cervical cells appear when infection or other irritation is around.

Epithelial cell abnormalities

This means that the cells lining the cervix or vagina show changes that might be cancer or a pre-cancer condition. This category is divided into several groups for squamous cells and glandular cells.

Squamous cell abnormalities

Atypical squamous cells (ASCs) This category includes two types of abnormalities:

• Atypical squamous cells of uncertain significance (ASC-US) is a term used when there are cells that look abnormal, but it is not possible to tell if this is caused by infection, irritation, or a pre-cancer. Most of the time, cells labeled ASC-US are not pre-cancer, but more testing is needed to be sure.
• Atypical squamous cells where high-grade squamous intraepithelial lesion (HSIL) can’t be excluded (ASC-H) is a term used when the cells look abnormal but are more concerning for a possible pre-cancer that needs more testing and may need treatment.

Squamous intraepithelial lesions (SILs) These abnormalities are divided into two categories:

• In low-grade SIL (LSIL) the cells look mildly abnormal.
• In high-grade SIL (HSIL) the cells look severely abnormal and are less likely than the cells in LSIL to go away without treatment. They are also more likely to eventually develop into cancer if they are not treated.

Further tests are needed if SIL is seen on a Pap test. This is discussed in  Work-up of abnormal Pap test results. If treatment is needed, it can cure most SILs and prevent true cancer from developing.

Squamous cell carcinoma:  This result means that the woman is likely to have an invasive cancer. Further testing will be done to be sure of the diagnosis before treatment can be planned.

Other malignant neoplasms

This category is for other types of cancer that hardly ever affect the cervix, such as malignant melanoma, sarcomas, and lymphoma.