Abnormal Pap and HPV

The liquid-based cytology test (PAP test) and the high-risk human papillomavirus (HPV) test are performed together from the same cell sample.  The tests are done by gently scraping cells off of the cervix with a spatula or brush.  The cell sample is placed in a special liquid and sent to a lab for processing and microscopic examination. An abnormal PAP test means the cervical cells are abnormal in appearance, but not necessarily pre-cancerous or cancerous.  A positive HPV test means that a high-risk, oncogenic HPV subtype was detected. In either case, your gynecologist may call you back for further testing.

Human papilloma viruses are a group of more than 200 related viruses. About 40 HPV viruses can be transmitted to the genital area by close skin-to-skin contact either without or with sex, including vaginal, anal, and oral sex. These genital HPVs can then infect cells of the female lower genital tract—the cervix, vagina, and vulva. They can be further transmitted to other organs, like the pharynx (the back of the throat) via oral sex.  In the U.S., genital HPV infection is the most common sexually-transmitted infection; it is so common that about 80% of American women will get at least one type of HPV infection at some point in their life.

Genital HPV subtypes that infect the lower genital tract are divided into two groups: (1) The low-risk subtypes, which do not cause cancer but cause vulvar and anal warts, and, as mentioned, (2) The high-risk subtypes, which can cause cervical, vaginal, vulvar (and anal) cancer.  About 12 genital HPV subtypes are high-risk. They have been detected in over 90% of cervical cancers and are considered to be the cause of these cancers. In fact, about 70% of cervical cancer cases are caused by high-risk genital HPV subtypes 16 and 18. The HPV test that is done concurrently with the PAP test (known as co-testing) is designed to detect the presence of high-risk genital HPV subtypes in cervical cells.

If a woman is exposed to genital HPV and an infection develops in the cervix with either low-risk or high-risk subtypes, fortunately the infection is naturally cleared by her immune system within two years 90% of the time (that is why a positive HPV test may then become negative later on). So, an HPV infection is usually not a problem. The problem occurs when, in a minority of women, an infection with a high-risk genital HPV subtype (especially HPV 16), is not cleared; the persistence of a high-risk HPV cervical infection can lead to pre-cancerous changes in the cervix known as severe dysplasia and even to cancer if appropriate surveillance and intervention are not exercised. That is why it is so vital for a woman who has been found to have abnormal cervical cancer screening to visit her gynecologist regularly as instructed.

Cervical dysplasia (also called CIN, or Cervical Intraepithelial Neoplasia) is the continuum of microscopic change toward invasive cancer that may occur over time in cells of the cervix that remain persistently infected with HPV. Cervical cancer screening with the PAP and HPV tests is actually a screen for cervical dysplasia.

Cervical dysplasia can progress from mild, to moderate, to severe (pre-cancer). Dysplastic cells are present on the surface or in the canal of the cervix and are picked up by the spatula and brush used during a PAP test. The PAP test is designed to detect dysplastic cells within the gathered cell sample. The PAP test can also detect the level of dysplasia the cells are exhibiting. As mentioned above, the HPV test is designed to detect the presence of the high-risk genital HPV subtypes in the cell sample. Neither test when abnormal is proof of the presence of cervical dysplasia; rather, it is indicative that cervical dysplasia may be present. That is why when either test is abnormal, further investigation is conducted and can lead to the diagnosis of dysplasia on a cervical biopsy (see section on Colposcopy/Biopsy). Because cervical dysplasia usually causes no signs or symptoms and can progress silently, it is very important for women to have their PAP and HPV testing according to established guidelines.

Cervical dysplasia is divided into low-risk and high-risk dysplasia categories. Low-risk cervical dysplasia is caused by low-risk HPV subtypes, and similarly, high-risk cervical dysplasia is caused by high-risk HPV subtypes.

Low-risk cervical dysplasia typically remains mild and can be safely monitored with cervical surveillance using a magnifying scope called a colposcope because its potential for progression to a cervical cancer is virtually none.  High-risk cervical dysplasia, however, can progress from mild to severe and further on to an invasive cancer over several years, so high-risk cervical dysplasia should be surgically removed to avoid such progression.