What are the possible findings of a Pap smear in asymptomatic females between 21 and 65 years old with no history of cervical cancer or abnormal Pap smears?

Pap Smear Findings in Average-Risk Women

Normal and Abnormal Results Classification

Pap smear results in asymptomatic women aged 21-65 years are reported using the 2001 Bethesda System, which categorizes findings as normal (negative for intraepithelial lesion or malignancy), unsatisfactory, or positive for abnormalities ranging from lowest to highest risk. 1

Normal Findings

• Negative for intraepithelial lesion or malignancy (NILM): This is the most common result, occurring in approximately 86-94% of screened women 2, 3
• The majority of asymptomatic women will have normal cytology results, with rates varying by age 1

Unsatisfactory Results

• Unsatisfactory for evaluation: Occurs in approximately 6% of samples and requires repeat testing 2, 3
• Even women with HPV-negative results should have unsatisfactory tests repeated, though colposcopy is an option for women aged 30 years or older 1

Abnormal Epithelial Cell Findings (Lowest to Highest Risk)

The following abnormalities are listed in order of increasing cancer risk 1:

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

• Most common abnormal finding, occurring in approximately 3-19% of abnormal smears 2, 3
• Carries a predicted 5-year risk of approximately 10% for CIN grade 2 or more severe lesion when combined with positive HPV testing 1
• Rates decrease with age: approximately 13% in women aged 21-24 years, 7% in those aged 30-34 years, and 3% in those aged 60-64 years 1

2. Low-Grade Squamous Intraepithelial Lesion (LSIL)

• Detected in approximately 4-7.5% of abnormal smears 2, 3
• Represents HPV-related changes and mild dysplasia 1

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

• Found in approximately 9-15% of abnormal smears 2
• Indicates suspicion for high-grade dysplasia but not definitive 1

4. High-Grade Squamous Intraepithelial Lesion (HSIL)

• Detected in approximately 0.5-5.5% of abnormal smears 4, 2, 3
• Carries a predicted 5-year risk of approximately 85% for CIN grade 2 or more severe lesion 1
• Represents moderate to severe dysplasia or carcinoma in situ 1

5. Squamous Cell Carcinoma

• Rare finding in screening, occurring in approximately 0.5-11% of abnormal smears 2
• Represents invasive cancer 1

6. Atypical Glandular Cells of Undetermined Significance (AGUS)

• Detected in approximately 4-6.5% of abnormal smears 2
• Requires further evaluation due to potential for adenocarcinoma 1

7. Adenocarcinoma

• Rare finding, occurring in approximately 3% of abnormal smears 2
• Represents glandular cell cancer 1

Inflammatory/Infectious Findings

• Inflammatory smear or evidence of infection: Found in approximately 13-43% of samples 5, 4, 3
• Does not represent precancerous or cancerous changes but indicates cervicitis or vaginitis 3

Age-Related Patterns

The prevalence of abnormal findings decreases significantly with age, reflecting the natural history of HPV infection 1:

• Women aged 21-24 years: approximately 13% have cytologic abnormalities and 30% have positive HPV results 1
• Women aged 30-34 years: approximately 7% have cytologic abnormalities and 12% have positive HPV results 1
• Women aged 60-64 years: approximately 3% have cytologic abnormalities and 5% have positive HPV results 1

Clinical Context

Most women undergoing screening are asymptomatic (approximately 15-82% in various studies), though some present with vaginal discharge (37-48%), irregular menstrual cycles (11-13%), or abdominal pain (8-26%) 5, 4, 3. The underlying prevalence of CIN grade 2 or more severe lesions ranges from 12% in women aged 21-24 years to 2.4% in those older than 50 years 1.