Abnormal Pap Smear Results: Understanding Cervical Cell Changes and Next Steps

An abnormal Pap result does not mean cancer. It indicates cervical cell changes (cervical intraepithelial neoplasia, CIN) that are precursors, most of which regress spontaneously.

Bethesda System Classification

• ASC-US: Atypical squamous cells of undetermined significance (lowest risk)
• LSIL (CIN 1): Low-grade squamous intraepithelial lesion – HPV-driven, 80–90% regress in 2 years
• ASC-H: Atypical squamous cells, cannot exclude HSIL
• HSIL (CIN 2/3): High-grade SIL – moderate/severe dysplasia; higher progression risk if untreated
• AGC: Atypical glandular cells – requires colposcopy + endocervical sampling ± endometrial biopsy
• AIS: Adenocarcinoma in situ

Management by Grade

ASC-US: Reflex HPV testing. HPV+ → colposcopy. HPV– → routine screening.
LSIL (CIN 1): Age 21–24: repeat Pap 12 mo. Age 25+: HPV+ → colposcopy; HPV– → repeat co-testing 12 mo.
HSIL (CIN 2/3): Colposcopy with biopsy. CIN 2: observe (age 21–24) or treat. CIN 3: treat (LEEP, cold knife cone, laser).
AGC/AIS: Colposcopy + endocervical curettage ± endometrial sampling.

Key Points

• HPV vaccination (9-valent) prevents 90% of cervical cancers; recommended through age 26, shared decision-making 27–45.
• Screening intervals: 21–29: Pap q3yr; 30–65: co-testing q5yr or Pap q3yr or HPV q5yr.
• Most HPV infections clear; persistence drives progression.
• Treatment preserves fertility in most cases.