A Pap smear’s primary purpose is to find abnormal cervical cells before they turn into cancer. The test collects cells from your cervix so they can be examined under a microscope for changes typically caused by HPV (human papillomavirus). Since widespread Pap screening began, cervical cancer incidence and mortality have dropped by roughly 70% in developed countries.
What the Test Actually Detects
A Pap smear looks for precancerous changes in the cells lining your cervix. These changes happen on a spectrum. In early stages, only about one-third of the cell layer’s thickness looks abnormal. In moderate stages, up to two-thirds is affected. In the most advanced precancerous stage, abnormal cells span more than two-thirds of the tissue. None of these stages are cancer yet, but without detection and treatment, they can progress to cervical cancer over a period of years.
This is what makes the test so valuable: it catches problems during a long window before cancer ever develops. Cervical cancer that is found early is also considerably easier to treat than cancer caught at a later stage.
How a Pap Smear Differs From an HPV Test
A Pap smear and an HPV test are related but do different things. The Pap smear examines the physical appearance of your cervical cells, looking for visible changes in shape or structure. An HPV test, by contrast, checks for the presence of high-risk strains of the virus itself. You can have HPV without any cell changes yet, and you can (rarely) have abnormal cells without a detectable HPV infection. The two tests complement each other, which is why they’re sometimes done together in what’s called cotesting.
When and How Often You Need One
Screening guidelines from the U.S. Preventive Services Task Force break down by age:
- Under 21: No screening recommended, regardless of sexual history.
- Ages 21 to 29: A Pap smear every 3 years.
- Ages 30 to 65: A Pap smear every 3 years, an HPV test alone every 5 years, or both tests together (cotesting) every 5 years.
- Over 65: Screening can stop if you’ve had adequate prior results, defined as three consecutive normal Pap results or two consecutive negative HPV results within the past 10 years, with the most recent test done within the last 5 years.
If you’ve had a hysterectomy that removed your cervix and you have no history of high-grade precancerous changes or cervical cancer, screening is no longer necessary.
How to Prepare
The test itself takes only a few minutes. Your provider inserts a speculum, then uses a small brush or spatula to gently collect cells from the surface of your cervix. Those cells are sent to a lab for analysis. Most people describe it as mildly uncomfortable rather than painful.
For the most accurate results, avoid intercourse, douching, and any vaginal medications, foams, creams, or jellies for two days before your appointment. These can wash away or obscure the cells the lab needs to see. Try not to schedule your test during your menstrual period. It can technically be done then, but it’s not ideal. However, if you’re experiencing bleeding outside your regular period, don’t delay the test.
What Happens If Results Are Abnormal
An abnormal result does not mean you have cancer. Most abnormal Pap smears reflect minor cell changes that your body may resolve on its own. What happens next depends on the type and severity of the abnormality, your previous screening history, any past treatments for precancerous changes, and your age.
Some results are more concerning than others. Minor changes in squamous cells (the flat cells covering the cervix) may only require a repeat test in a year. But certain findings will prompt your provider to recommend a colposcopy, a closer examination of your cervix using a magnifying instrument, often with a small tissue biopsy. These include:
- High-grade squamous intraepithelial lesions (HSIL): Moderately or severely abnormal cells that could become cancer if untreated.
- Atypical squamous cells that may be high-grade (ASC-H): Cells that look suspicious but aren’t definitively high-grade yet.
- Atypical glandular cells (AGC): Unusual cells from the glandular tissue of the cervix or uterus, which can signal a more serious problem.
- Adenocarcinoma in situ (AIS): An advanced precancerous change in glandular tissue that will likely become cancer if left alone.
A colposcopy is done in your provider’s office and feels similar to the Pap smear itself, though a biopsy may cause brief cramping. If precancerous cells are confirmed, several outpatient treatments can remove the abnormal tissue before it ever becomes cancer. This is the entire point of the screening process: catching and treating changes years before they would pose a real threat.
Why Screening Still Matters With the HPV Vaccine
The HPV vaccine dramatically reduces the risk of the virus strains most likely to cause cervical cancer, but it doesn’t eliminate the need for Pap smears. The vaccine doesn’t cover every cancer-causing HPV strain, and many adults were not vaccinated before they were exposed to the virus. Current screening guidelines apply the same way whether or not you’ve been vaccinated. The combination of vaccination and regular screening is what gives the strongest protection against cervical cancer.