Cervical Cancer Prevention and Early Detection

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The Pap (Papanicolaou) test

The Pap test is the main screening test for cervical cancer and pre-cancerous changes. A woman should know how it is done and how often they should have a Pap test.

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 cell samples are then prepared so that they can be examined under a microscope in the laboratory. This this is done either by:

  • Smearing the sample directly onto a glass microscope slide and spraying it with a preservative. The slide is then sent to the laboratory. This is called conventional cytology.
  • Putting the sample of cells from the cervix into a special preservative liquid (instead of putting them on a slide directly). The bottle containing the cells and the liquid is sent to the lab. The cells in the liquid are spread onto slides in the lab. This is called liquid-based cytology, or a liquid-based Pap test.

Liquid-based testing does not find more cancers or pre-cancers than conventional cytology but it does have some advantages. These include a lower chance that the Pap test will need to be repeated, and the ability to use the same sample for HPV testing. A drawback of the liquid-based test is that it is more likely to find cell changes that are not pre-cancerous but that will need to be checked out further − leading to unnecessary tests. This method is also more expensive than conventional cytology.

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 humans, 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 laboratories), it’s not a good idea to have this test less often than American Cancer Society guidelines recommend. Unfortunately, many of the women most at risk for cervical cancer are not being tested often enough or at all.

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 test.
  • Don't douche for 2 to 3 days before the test.
  • Don’t have sexual intercourse for 2 days before the 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. Pap tests are often done during pelvic exams, but you can have a pelvic exam without having a Pap test. A pelvic exam without a Pap test will not help find abnormal cells of the cervix or cervical cancer at an early stage.

The Pap test is often done during a pelvic exam, after the speculum is placed. To do a Pap test, the doctor removes cells from the cervix by gently scraping or brushing it with a special instrument. Pelvic exams may help find other types of cancers and reproductive problems, 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.

Negative for intraepithelial lesion or malignancy

This first category means that no signs of cancer, pre-cancerous changes, or other significant abnormalities were found. Some specimens in this category appear entirely normal. Others may have 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 respond to infection or other irritation.

Epithelial cell abnormalities

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

Squamous cell abnormalities

Atypical squamous cells (ASCs): This category includes atypical squamous cells of uncertain significance (ASC-US) and atypical squamous cells where high-grade squamous intraepithelial lesion (SIL) can’t be excluded (ASC-H).

ASC-US is a term used when there are cells that look abnormal, but it is not possible to tell (by looking at the cells under a microscope) if this is caused by infection, irritation, or if it is a pre-cancer. Most of the time, cells labeled ASC-US are not pre-cancer, but more testing is needed to be sure.

If the results of a Pap test are labeled ASC-H, it means that a SIL is suspected.

Pap test results of either type of ASC mean that more testing is needed. This is discussed in the section, “Work-up of abnormal Pap test results.”

Squamous intraepithelial lesions (SILs): These abnormalities are subdivided into low-grade SIL (LSIL) and high-grade SIL (HSIL). In LSIL, the cells are mildly abnormal, while in HSIL, the cells are severely abnormal. HSILs are less likely than LSILs to go away without treatment. They are also more likely to eventually develop into cancer if they are not treated. Treatment can cure most SILs and prevent true cancer from developing.

Further tests are needed if SIL is seen on a Pap test. This is discussed in the section, “Work-up of abnormal Pap test results.”

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.

Glandular cell abnormalities

Adenocarcinoma: Cancers of the glandular cells are called adenocarcinomas. In some cases, the pathologist examining the cells can tell whether the adenocarcinoma started in the endocervix, in the uterus (endometrium), or elsewhere in the body.

Atypical glandular cells: When the glandular cells do not look normal, but have features that do not permit a clear decision as to whether they are cancerous, the term used is atypical glandular cells (AGCs). The patient should have more testing if her cervical cytology result shows atypical glandular cells.

Other malignant neoplasms

This category is for forms of cancer that only rarely affect the cervix, such as malignant melanoma, sarcomas, and lymphoma.

Other descriptions of Pap test results have also been used in the past.

Last Medical Review: 09/17/2014
Last Revised: 07/19/2016