Abnormal Pap Smear Results: What the Terms Mean and What Happens Next

What do the result categories mean?

Pap smear results use standardized language that describes how abnormal cervical cells appear under a microscope [1, 2]:

• ASCUS (Atypical Squamous Cells of Undetermined Significance): the most common abnormal result. Cells look slightly unusual but the cause is unclear. Often related to a transient HPV infection or inflammation.
• LSIL (Low-Grade Squamous Intraepithelial Lesion): mild cell changes. The majority resolve without treatment, particularly in younger people.
• HSIL (High-Grade Squamous Intraepithelial Lesion): more significant changes that require prompt follow-up. A smaller proportion of these may progress if left unaddressed.
• ASC-H: atypical squamous cells where high-grade changes cannot be ruled out — warrants colposcopy.
• AGC (Atypical Glandular Cells): involves a different cell type and requires a thorough evaluation. This is less common but important not to overlook.

Results frequently include a simultaneous HPV co-test, since high-risk HPV strains drive the vast majority of cervical cell changes and virtually all cervical cancers 2Ref 2American College of Obstetricians and Gynecologists (2023).Colposcopy and Cervical Biopsies (Patient FAQ).Result category definitions (ASCUS, LSIL, HSIL, AGC), HPV co-testing significance, and colposcopy indication guidance.

What typically happens next?

The recommended follow-up is not one-size-fits-all — it depends on the specific result grade, your HPV test result, your age, and your prior screening history [1, 2].

• ASCUS with a negative HPV test: risk of significant disease is low; guidelines generally recommend returning in three to five years.
• ASCUS with a positive high-risk HPV test, or LSIL: colposcopy is usually the next step.
• HSIL or ASC-H: colposcopy is recommended promptly.
• AGC: requires more extensive evaluation.

For people under 25, LSIL is very likely to resolve without treatment, and guidelines reflect that age-specific context. After 65 with an adequate history of normal screening, cervical cancer screening can often be discontinued — a conversation to have with your clinician.

What does colposcopy involve?

A colposcopy is done in an office or clinic. A speculum is used just as with a Pap smear, and a magnifying device called a colposcope gives the clinician a detailed view of the cervix. A dilute acidic solution may be applied to make any abnormal areas more visible. If something looks concerning, a small biopsy is taken — this may cause brief cramping. Biopsy results typically take one to two weeks and guide the next decision: watchful waiting, repeat testing, or a minor treatment procedure 3Ref 3American College of Obstetricians and Gynecologists (2020).Vaginitis in Nonpregnant Patients: ACOG Practice Bulletin, Number 215.Context for non-infectious causes of ASCUS (inflammation, hormonal effects) and the role of clinical evaluation in distinguishing causes.

If the biopsy confirms a precancerous change (cervical intraepithelial neoplasia, or CIN), treatment usually involves removing the abnormal tissue with a brief outpatient procedure such as LEEP (loop electrosurgical excision) or cryotherapy. These procedures are generally effective and well-tolerated.

Why does HPV matter so much here?

High-risk strains of HPV — particularly HPV 16 and 18 — are responsible for the overwhelming majority of cervical cell changes and cervical cancers. HPV vaccination, especially when completed before sexual debut, substantially reduces the risk of infection with these strains 4Ref 4Meites E, Szilagyi PG, Chesson HW, Unger ER, Romero JR, Markowitz LE (2019).Human Papillomavirus Vaccination for Adults: Updated Recommendations of the Advisory Committee on Immunization Practices.HPV vaccination substantially reduces risk of high-risk HPV strains; continued screening still recommended for vaccinated individuals. Vaccination does not eliminate the need for continued cervical screening, but it does lower the population-level risk of the changes that Pap smears are designed to catch.

Smoking is a cofactor that makes it harder for the immune system to clear HPV, increasing the likelihood that cell changes persist or progress. People who smoke and have an abnormal result should discuss this with their clinician. Immunosuppression — including HIV — is also associated with faster progression of cell changes and shorter recommended screening intervals 1Ref 1US Preventive Services Task Force (2018).Screening for Cervical Cancer: US Preventive Services Task Force Recommendation Statement.Cervical cancer screening intervals, age-specific recommendations, co-testing guidance, and follow-up after abnormal results.

Will an abnormal result need treatment?

Many abnormal Pap results, especially mild ones, do not require treatment. The immune system clears the underlying HPV infection and cells return to normal. When treatment is needed, it is typically a brief outpatient procedure that is well-tolerated for most people and does not affect future fertility in most cases, though individual considerations apply [1, 3].

The most important thing to do with any abnormal result is follow through on the recommended next step — whether that is a repeat Pap or a colposcopy appointment. The screening system works when people act on its findings.