How do I interpret a Pap smear report for an asymptomatic female between 21 and 65 years old with no history of cervical cancer or abnormal Pap smears?

How to Interpret a Pap Smear Report

Pap smear reports use the Bethesda System terminology to categorize cervical cytology findings, ranging from normal (negative for intraepithelial lesion or malignancy) to various grades of abnormalities that indicate increasing cancer risk and guide specific management pathways. 1

Understanding the Bethesda System Categories

The 2001 Bethesda System provides standardized terminology that you'll see on every Pap smear report 1:

Normal Results

• Negative for Intraepithelial Lesion or Malignancy (NILM): This is the most common result, seen in approximately 86% of screened women 2. This indicates no cellular abnormalities detected and the patient can continue routine screening intervals 1.

Unsatisfactory Results

• Unsatisfactory for evaluation: The specimen lacks adequate cells or is obscured by blood/inflammation 1. These should be repeated even in women with HPV-negative results, though colposcopy is an option for women aged 30 years or older 1.

Abnormal Results (Listed from Lowest to Highest Cancer Risk)

1. Atypical Squamous Cells of Undetermined Significance (ASC-US)

• The most common abnormality, representing approximately 42-43% of abnormal smears 2
• Carries approximately 10% predicted 5-year risk for CIN 2 or worse when combined with positive HPV testing 1
• Management: Requires HPV testing for triage in women aged ≥21 years 1, 3

2. Low-Grade Squamous Intraepithelial Lesion (LSIL)

• Represents approximately 6-7% of abnormal smears 2
• Indicates HPV infection with mild dysplastic changes 1
• Management: Typically requires colposcopy for further evaluation 1

3. Atypical Squamous Cells—Cannot Exclude High-Grade Dysplasia (ASC-H)

• Represents approximately 15% of abnormal smears 2
• Suggests possible high-grade lesion but findings are not definitive 1
• Management: Requires colposcopy due to higher cancer risk 1

4. High-Grade Squamous Intraepithelial Lesion (HSIL)

• Represents approximately 15% of abnormal smears 2
• Carries approximately 85% predicted 5-year risk for CIN 2 or worse 1
• Shows the highest cytohistopathological correlation at 88.89% 2
• Management: Immediate colposcopy with biopsy is mandatory 1

5. Invasive Squamous Cell Carcinoma

• Represents approximately 11% of abnormal smears 2
• Indicates frank malignancy requiring urgent referral 1

6. Adenocarcinoma

• Represents approximately 3% of abnormal smears 2
• Indicates glandular malignancy requiring urgent referral 1

7. Atypical Glandular Cells of Undetermined Significance (AGUS)

• Represents approximately 7% of abnormal smears 2
• Requires colposcopy and often endocervical sampling 1

Age-Specific Context for Interpretation

Women Aged 21-29 Years

• Cytologic abnormalities occur in approximately 13% of this age group 1
• HPV positivity is very common (30%) due to recent sexual activity initiation, but most infections are transient 1
• The prevalence of CIN 2 or worse is approximately 12% in this age group 1

Women Aged 30-65 Years

• Cytologic abnormalities decrease to approximately 3-7% 1
• HPV positivity decreases significantly (5-12%) 1
• The prevalence of CIN 2 or worse decreases to approximately 2.4% in women over 50 years 1

Critical Management Principle

The guiding principle is "similar management for similar risks" 1. This means that different combinations of cytology and HPV results that carry the same cancer risk receive the same management approach, regardless of how that risk level was reached.

Common Pitfalls to Avoid

• Do not equate a pelvic examination with obtaining a Pap test: Many women erroneously believe a Pap sample was taken when only a pelvic exam was performed 1. Always document specifically whether cytology was collected.

• Inflammatory smears require clinical correlation: Approximately 32% of smears show inflammatory changes 4. Persistent inflammation unresponsive to appropriate therapy requires colposcopy to exclude underlying dysplasia 5.

• Adequate sampling is essential: Use both spatula and Cytobrush to ensure endocervical cells are collected, which improves sample adequacy 5.

• HPV testing has age restrictions: Never use HPV testing as a standalone screening test in women under 25 years or for STD screening purposes 1, 6.