Cervical cancer screening and prevention
- Technique
Cervical cancer takes years to develop from a visible precursor; screening finds it in that window and the vaccine stops the infection that starts it.
What it is
Cervical cancer is one of the most preventable cancers because its precursor lasts years and lives on a surface that can be sampled. Screening uses cytology (the Pap test), testing for high-risk HPV, or both; abnormal results lead to colposcopy, biopsy and treatment of high-grade lesions. Vaccination against HPV, given before sexual exposure, prevents the infections behind most cases, but vaccinated women still need screening.
Step by step
- Sample: a brush collects cells from the ectocervix, the transformation zone and the endocervical canal.
- Test: the sample is tested for high-risk HPV, read as cytology, or both.
- Triage: positive results are sorted by HPV type, cytology or other markers to decide who needs colposcopy.
- Colposcopy and biopsy confirm whether there is HSIL, adenocarcinoma in situ or invasion.
- Treatment removes high-grade lesions; follow-up testing confirms clearance.
Bethesda cytology categories and what they mean
| Category | Meaning | Usual next step |
|---|---|---|
| NILM | No intraepithelial lesion or malignancy | Routine screening |
| ASC-US | Atypical squamous cells of undetermined significance | HPV test or repeat cytology |
| ASC-H | Atypical squamous cells, cannot exclude HSIL | Colposcopy |
| LSIL | Low-grade squamous intraepithelial lesion | Colposcopy or follow-up depending on age and HPV |
| HSIL | High-grade squamous intraepithelial lesion | Colposcopy and treatment |
| AGC or AIS | Atypical glandular cells or adenocarcinoma in situ | Colposcopy and endocervical (and often endometrial) sampling |
Clinical notes
- Most cervical cancers occur in women who were never screened or who were not followed up after an abnormal result.
- Colombia vaccinates schoolgirls against HPV and screens with cytology and HPV testing; access and follow-up remain uneven between cities and rural areas.
- Screening is a public-health tool: the exact ages and intervals follow each country's guideline.
Test yourself
Think of the answer, then tap the question to see it.
Why does cervical cancer screening work so well?
The precursor lasts years, sits on an accessible surface that can be sampled, and can be treated simply before it invades.
What does ASC-H mean on a Pap report?
Atypical squamous cells for which a high-grade lesion cannot be excluded; colposcopy is indicated.
Do vaccinated women still need screening, and why?
Yes; vaccines do not cover every high-risk type and do not clear infections already present.
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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Cervical Cancer Screening (PDQ®)–Health Professional Version (National Cancer Institute, 2026); Human Papillomavirus (StatPearls (NCBI Bookshelf), 2026); Cervical cancer mortality among young women in Latin America and the Caribbean: trend analysis from 1997 to 2030 (BMC public health, 2022).
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Representative model, for educational purposes only.