The changes that oncogenic HPV types
cause in cells can frequently be detected by using a test referred
to as the "Pap test" or "Pap smear". This test
requires that a small number of cells be examined under microscope.
Colored stains are used to make the cells and any unusual changes
within them more apparent.
Doctors, nurse practitioners and physician’s
assistants gather the cells for the Pap test using a tiny brush
or spatula. Cervical Pap tests (smears) are the most commonly performed
tests used to detect pre-cancerous changes. Anal Pap tests similarly
examine cells from the anal canal for precancerous changes.
Not all Pap tests results are created
equally. The accuracy of a Pap test depends upon the quality of
the sample that is collected, the skill of the doctor or nurse obtaining
the cells from the cervix or anal canal and the skill of the technician
and pathologist who interprets the test results. New screening tools
have become available that allow us to gather and preserve a larger
number of cervical or anal cells for screening (e.g., Thin Prep
and cytobrushes). Some automated, computerized screening systems
are being tested and used in a few clinics to aid pathologists in
diagnosing precancerous changes more accurately.