Pap Testing

last authored: Jan 2012, David LaPierre
last reviewed: July 2015, Dawn Lambert




Cervical cancer, which is caused almost completely by infection with the human papillomavirus, is almost completely preventable through effective screening and identification of precancerous changes or early cancers. This is done primarily through Pap testing (short for Papanicolaou test, named after it's originator).


All women who are, or who have been, sexually active should be screened. We suggest pap testing should be commenced within three years of first vaginal sexual activity (intercourse, oral, digital, shared devices). If people have NOT been sexually active, their risk of HPV infection and development of cervical malignancy is very low, and the need for Pap testing is also low.





A speculum exam is required for cervical visualization. This is discussed here.

There are various methods of sampling the cervix once it is in view. Cytologic smears can be taken of the endocervix with tools such as a spatula, the brush, and the broom.


In settings where microscopic analysis is not available, visual inspection with 3-5% acetic acid (VIA) can be done. Acetic acid irritates the cervix and causes vasodilation while also turning areas of cervical dysplasia white. Numerous studies have examined the success of VIA, and yield sensitivity of 66-96% and specificity of 64-98% (Gaffikin, Lauterbach, and Blumenthal, 2003).


Programs exist to guide delivery of competency-based training programs in VIA (Blumenthal et al, 2005).

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Screening Guidelines

Guidelines vary by region. For example, in Ontario, screening should be initiated within three years of sexual intercourse (including oral and digital). Screening should occur yearly until there are three negative results, at which point screening may occur every 2-3 years. If a woman has not been screened in five years, the screening pattern should be reset. Screening may be discontinued at age 70 if there have been no positive results in the previous 10 years.

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Abnormal Pap Smears

The nature of the results suggest a plan of action.


Smear Results

Unsatisfactory: sample was not adequate. Repeat testing is suggested.

Benign: no malignancy, but changes that might suggest infection or inflammation

Atypical cells of uncertain significance: abnormal squamous cells (ASCUS) or glandular cells (AGCUS) that may or may not be a sign of malignant potential. Repeat testing is suggested.

Low-Grade changes (mild dysplasia, or CIN I): atypical changes suggesting malignant potential. Colposcopy is usually recommended.

High-Grade changes (moderate or severe dysplasia, carcinoma in situ, or CIN II or III): very atypical cells with high risk of malignant progression. Colposcopy is recommended.

Squamous cell carcinoma or adenocarcinoma: cancer is present. Colposcopy is immediately recommended.



Acetic acid results

Abnormal results from VIA should be referred for colposcopy. These include opaque, white lesions:

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Resources and References

Blumenthal PD et al. 2005. Training for cervical cancer prevention programs in low-resource settings: focus on visual inspection with acetic acid and cryotherapy. Int J Gynaecol Obstet. 89 Suppl 2:S30-7.

Gaffikin L, Lauterbach M, Blumenthal PD. 2003. Performance of visual inspection with acetic acid for cervical cancer screening: a qualitative summary of evidence to date. Obstet Gynecol Surv. 58(8):543-50.

Megevand E et al. 1996. Acetic acid visualization of the cervix: an alternative to cytologic screening. Obstet Gynecol. 88(3):383-6.

PapTestsinfo - Society of Canadian Colposcopists

Cancer Care Ontario - cervical cancer screening guidelines

US Preventive Services Task Force - Cervical Cancer Screening Recommendations

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