Smear test results: PAP classification explained
Have you received the results of your smear test and want to understand what it means? On this page, we clearly explain the PAP system, from PAP 1 to PAP 5.
What is the PAP system?
The PAP system (named after the Greek physician Georgios Papanicolaou) is a classification system used to evaluate the results of a smear test. It describes whether abnormal cells have been found on the cervix and, if so, how severe the abnormalities are.
A smear test (also called cervical cytology) is an examination in which cells are taken from the cervix and viewed under a microscope. The goal is to detect abnormalities early that, if left untreated, could eventually develop into cervical cancer.
The PAP classification ranges from PAP 1 (normal) to PAP 5 (suspected invasive carcinoma). Below you will find an overview of all results and what they mean.
Overview of PAP results
PAP classification
| PAP result | Meaning | Severity | Follow-up action |
|---|---|---|---|
| PAP 1 | Normal, no abnormalities | None | Regular screening program (every 5 years) |
| PAP 2 | Slight abnormalities, often due to inflammation | Minimal | Repeat smear test after 6-12 months |
| PAP 3a | Mild to moderate abnormalities (most common abnormal result) | Mild-moderate | HPV test and/or referral to gynecologist |
| PAP 3b | More severe abnormalities | Moderate-severe | Referral to gynecologist for colposcopy |
| PAP 4 | Possible carcinoma in situ | Severe | Treatment by gynecologist |
| PAP 5 | Almost certainly cervical cancer | Very severe | Treatment by gynecologist |
Each result explained
PAP 1: Normal
A PAP 1 result means that no abnormal cells were found. This is the result you want to see. You will be invited again for the regular screening program according to the standard schedule. Please note: a PAP 1 result does not always exclude an HPV infection, depending on the test used.
PAP 2: Slight abnormalities
With a PAP 2 result, slight cell changes have been found. These are often caused by inflammation, hormonal changes, or a recently placed IUD. In most cases, these abnormalities are harmless and disappear on their own. A repeat smear test after 6 to 12 months is recommended.
PAP 3a: Mild to moderate abnormalities
PAP 3a is the most common abnormal result. It means that mild to moderate cell abnormalities have been found. A referral to the gynecologist for a colposcopy (visual examination of the cervix) will follow. PAP 3a usually corresponds to CIN 1 or CIN 2 upon biopsy, but it can also be CIN 3.
PAP 3b: More severe abnormalities
A PAP 3b result indicates more severe cell abnormalities. The chance of an underlying CIN 2 or CIN 3 is greater than with PAP 3a. You will be referred to the gynecologist for a colposcopy and biopsy.
PAP 4: Severe abnormalities
With a PAP 4 result, there is a suspicion of carcinoma in situ: cells that are highly abnormal but have not yet grown into the surrounding tissue. This requires immediate referral to the gynecologist for further investigation and treatment.
PAP 5: Suspected invasive carcinoma
A PAP 5 result is the most serious outcome. There is a suspicion of an invasive carcinoma, where abnormal cells may have grown into deeper tissue. This requires an urgent referral to the gynecologist for immediate further diagnostics and treatment.
Difference between PAP and CIN
PAP and CIN are often confused, but they are two different classification systems that each measure something different:
PAP vs. CIN
| PAP classification | CIN classification | |
|---|---|---|
| What is assessed | Cells from the smear test (cytology) | Tissue from biopsy (histology) |
| Method | Microscopic examination of loose cells | Microscopic examination of a tissue sample |
| When | During smear test / screening program | After referral to gynecologist |
| Scale | PAP 1 through PAP 5 | CIN 1 through CIN 3 |
| Accuracy | Screening method (indicative) | Diagnostic method (definitive) |
In short: the PAP system is a screening method based on loose cells. It gives an indication of possible abnormalities. The CIN system is a diagnostic method based on a tissue examination (biopsy) and provides a more definitive assessment of the severity of the abnormalities.
A PAP 3a result can yield CIN 1 or CIN 2 upon biopsy. A PAP 3b can be CIN 2 or CIN 3. The PAP result is therefore always an estimate that is confirmed or adjusted by the biopsy.
Read more per result
Did you receive an abnormal smear test result?
It is understandable that an abnormal result causes anxiety. At HPV Health, we help you understand the result and discuss what steps you can take. Feel free to contact us.
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