The Pap test is a procedure that collects cells from the cervix so that they can be looked at closely in the lab 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 or brush, a sample of cells and mucus is lightly scraped from the exocervix (see illustration in What is Cervical Cancer? ). A small brush or a cotton-tipped swab is then inserted into the opening of the cervix to take a sample from the endocervix . 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 from the upper part of the vagina (known as the vaginal cuff) will be sampled. The samples are then looked at 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 best to have this test regularly as recommended by the American Cancer Society guidelines .
You can do several things to make your Pap test as accurate as possible:
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. A Pap test can be done during a pelvic exam , but sometimes a pelvic exam is done without a Pap test. A Pap test is needed to find early cervical cancer or pre-cancers so ask your doctor if you had a Pap test with your pelvic exam.
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:
You may need further testing if your Pap test showed any of the abnormalities below. See Work-up of Abnormal Pap Test Results.
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 type of sexually transmitted disease), for example. Specimens from some women may also show “reactive cellular changes”, which is the way cervical cells appear when infection or other inflammation is around.
This means that the cells lining the cervix or vagina show changes that might be cancer or a pre-cancer. This category is divided into several groups for squamous cells and glandular cells.
Atypical squamous cells (ASCs) This category includes two types of abnormalities:
Squamous intraepithelial lesions (SILs) These abnormalities are divided into two categories:
Further tests are needed if SIL is seen on a Pap test. If treatment is needed, it can cure most SILs and prevent invasive cancer from forming.
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.
Atypical glandular cells: When the glandular cells do not look normal, but they have concerning features that could be cancerous, the term used is atypical glandular cells (AGC). In this case, the patient should have more testing done.
Adenocarcinoma: Cancers of the glandular cells are called adenocarcinomas. In some cases, the doctor examining the cells can tell whether the adenocarcinoma started in the endocervix, in the uterus (endometrium), or elsewhere in the body.
This category is for other types of cancer that hardly ever affect the cervix, such as malignant melanoma, sarcomas, and lymphoma.
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.
Eifel P, Klopp AH, Berek JS, and Konstantinopoulos A. Chapter 74: Cancer of the Cervix, Vagina, and Vulva. In: DeVita VT, Lawrence TS, Rosenberg SA, eds. DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 11th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2019.
Jhungran A, Russell AH, Seiden MV, Duska LR, Goodman A, Lee S, et al. Chapter 84: Cancers of the Cervix, Vulva, and Vagina. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 6th ed. Philadelphia, Pa: Elsevier; 2020.
National Cancer Institute. Physician Data Query (PDQ). Cervical Cancer Treatment – Health Professional Version. 2019. https://www.cancer.gov/types/cervical/hp/cervical-treatment-pdq. Updated February 6, 2019. Accessed on October 30, 2019.
National Cancer Institute. Understanding Cervical Changes: Next Steps After an Abnormal Screening Test. 2019. https://www.cancer.gov/types/cervical/understanding-cervical-changes#ui-id-2. Updated October 8, 2019. Accessed on November 1, 2019.
Last Revised: January 3, 2020
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