A Pap test is a procedure that removes a small sample of cells from the cervix. It is done to look for changes to the cells in the cervix.
Why a Pap test is done
A Pap test is mainly used to:
- screen for and help diagnose precancerous conditions of the cervix and cervical cancer
- help diagnose precancerous conditions of the vagina and vaginal cancer
- diagnose infection and inflammation in the lower female reproductive tract
- follow up after an abnormal Pap test or to monitor precancerous conditions
- check for abnormal cell changes or to see if cancer comes back (recurs) after treatment
How a Pap test is done
To prepare for a Pap test:
- Book your appointment for when you are not having your period.
- Don’t have sexual intercourse for at least 24 hours before your Pap test.
- Don’t use vaginal douches, vaginal medicines, vaginal sprays or powders, or contraceptive creams for at least 24 hours before your Pap test.
- Don’t have a Pap test if you are being treated for a cervical or vaginal infection. Wait at least 2 weeks after treatment has ended before having a Pap test.
- Empty your bladder before the Pap test.
A Pap test may be done as part of a regular checkup or during a pelvic exam. It is usually done in a doctor’s or nurse’s office or in a clinic. It only takes a few minutes. You may feel some discomfort or pressure during the procedure, but it is not usually painful.
During a Pap test you lie on your back with your feet up in stirrups. The doctor or nurse places a speculum (a clear plastic or metal device) into the vagina. The speculum keeps the vagina open so they can see the upper part of the vagina and cervix. Using a small stick, spatula, and/or brush the doctor or nurse gently scrapes the surface of the cervix to pick up cells. Sometimes they will use a special brush to collect cells from the inner part of the cervix that leads into the uterus. Samples of cells from the vagina can also be taken during a Pap test.
The collected cells are placed in a special liquid. The sample is sent to a lab to be examined under a microscope. If the cells are placed in a container filled with a special liquid, it is called a liquid-based Pap test. The liquid containing the sample of cells may also be used to test for the human papillomavirus (HPV).
You may have some light bleeding from the vagina after a Pap test.
Find out more about a pelvic exam.
What the results mean
A Pap test result may be described as normal or abnormal. Normal results are also sometimes described as negative.
A normal result means that no abnormal or cancerous cells were found.
Abnormal Pap test results
If your Pap test results are abnormal, it doesn’t always mean that you have a precancerous condition or cancer. Some abnormal cells return to normal on their own. Other abnormal cells or precancerous changes in the cervix or vagina may develop into cancer over time if they aren’t treated.
Abnormal cells in the cervix or vagina are classified based on the type of cell that has changed and how different they look from normal cells. How abnormal they are may be described as low or high grade.
Squamous cells come from the surface of the cervix or vagina. Glandular cells come from the inside of the cervical canal.
Squamous cell changes are described as squamous intraepithelial lesion (SIL). SIL is described as low grade (least severe) or high grade (most severe).
- Atypical squamous cells (ASC) means the cells don’t look normal. It is the most common finding.
- Atypical squamous cells – undetermined significance (ASC-US) means some cells don’t look completely normal.
- Low-grade squamous intraepithelial lesion (LSIL) means the cells have mild changes in size and shape, caused by an HPV infection.
- Atypical squamous cells (ASC-H) means the cells don’t look normal but it’s not clear what the changes mean. The abnormal cells could be a high-grade lesion.
- High-grade squamous intraepithelial lesion (HSIL) means there are abnormal or precancerous cells present and they have a higher chance of progressing to cancer.
- Squamous cell carcinoma (SCC) means there are cancer cells in the lining of the outer surface of the cervix.
Glandular cell changes are described as:
- Atypical glandular cells (AGC) means the cells don’t look normal.
- Adenocarcinoma in situ (AIS) means there are cancer cells in the glandular tissue lining the inside of the cervix but there has been no spread into the deeper tissues of the cervix or surrounding tissue.
- Adenocarcinoma means there is cancer in the lining inside the cervix (endocervical cancer).
What caused the changes?
Infection with HPV is the most common cause of changes to cervical cells. Sometimes cells infected with HPV can become precancerous. Changes to the cervix may also be caused by:
- viral, bacterial or yeast infection
- non-cancerous growths such as polyps or cysts
What happens if the results are abnormal
Your doctor may recommend more tests, procedures, follow-up care or treatment.
Follow-up options for abnormal results
Follow-up for an abnormal Pap test depends on how severe the results are. Some abnormalities may not need to be treated because some abnormal cells change back to normal on their own. Other abnormal cells or precancerous changes to cells may develop into cancer if they aren’t treated.
Follow-up tests and treatment for abnormal Pap test results include:
- another Pap test
- an HPV test
- a colposcopy (a procedure that uses a lighted magnifying instrument, called a colposcope, to examine the vulva, vagina and cervix)
- endocervical curettage (a type of biopsy to remove cells from the endocervical canal, which is the passageway from the uterus to the vagina)
- a loop electrosurgical excision procedure (LEEP) or other type of cone biopsy
Pregnancy and abnormal Pap test results
If you have an abnormal Pap test result when you are pregnant, your doctor will talk to you about next steps. You may have a colposcopy. But doctors usually avoid taking a biopsy until after you have given birth because there is a small chance that taking a biopsy sample can cause bleeding.
Risks with a Pap test
Screening tests, including the Pap test, have a risk of giving misleading results.
A false-negative result means that the test doesn’t find cancer or abnormal cells even though they are present. This may occur if the sample doesn’t have enough tissue or cells. It can also happen when abnormal cells in the sample are missed.
A false-positive result means that the test shows abnormal cells even though they are not present. This means that something looks like a precancerous condition, but it actually isn’t. A false-positive result may lead to unnecessary follow-up tests, procedures and anxiety.
Research at the Canadian Centre for Applied Research in Cancer Control led to a new standard in leukemia testing.
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