Who should undergo an anal Pap (Papanicolaou) test?

Anal Pap Screening Guidelines

Anal Pap tests should be performed in HIV-infected men who have sex with men (MSM), women with a history of receptive anal intercourse or abnormal cervical Pap test results, and all HIV-infected persons with genital warts. 1

High-Risk Populations Requiring Anal Pap Screening

Anal cancer screening with cytology (anal Pap test) is recommended for specific high-risk populations:

1. HIV-infected individuals:

   • All HIV-infected MSM
   • HIV-infected women with history of abnormal cervical Pap tests
   • HIV-infected persons with genital warts
   • HIV-infected men and women with HPV infection

2. Non-HIV-infected individuals:

   • MSM with history of receptive anal intercourse
   • Women with history of receptive anal intercourse
   • Women with history of cervical or vulvar cancer or high-grade cervical lesions
   • Immunocompromised men and women 2

Rationale for Screening

The rationale for targeted anal Pap screening is based on increased risk of anal dysplasia and cancer in these populations:

• HIV-infected MSM have substantially higher anal cancer incidence (80-131 cases per 100,000 person-years) compared to the general population (1-2 cases per 100,000 person-years) 1
• HIV-infected men have 40-60 cases per 100,000 person-years
• HIV-infected women have 20-30 cases per 100,000 person-years
• MSM without HIV infection have 14 cases per 100,000 person-years 1

Screening Protocol

If anal cytologic screening is performed and indicates abnormal findings:

1. High-resolution anoscopy (HRA) should be performed
2. Biopsy of abnormal areas should be conducted
3. Appropriate therapy based on biopsy results should be initiated 1

Important Considerations

• Sensitivity and specificity of anal cytology to detect high-grade squamous intraepithelial lesions (HSIL) are limited (sensitivity 55%-89% and specificity 40%-67%) 1
• Health centers that initiate cytology-based screening programs should only do so if referrals to HRA and biopsy are available 1
• Annual digital anorectal examination (DARE) might be useful to detect masses on palpation in persons with HIV infection and MSM without HIV with a history of receptive anal intercourse 1

Patient Acceptance

Research shows high acceptance of anal Pap screening among both HIV-infected and non-HIV-infected MSM across multiple US sites (85% acceptance rate). Most patients report the experience as "not a big deal" or "not as bad as expected" 3.

Limitations and Caveats

• Current guidelines provide a weak recommendation with moderate quality evidence for anal Pap tests in high-risk populations 1
• Data are insufficient to recommend routine anal cancer screening with anal cytology in the general population 1
• More evidence is needed concerning the natural history of anal intraepithelial neoplasia, optimal screening methods, target populations, and treatment safety before screening can be routinely recommended for broader populations 1

While the Infectious Diseases Society of America recommends anal Pap tests for specific high-risk populations, clinicians should be aware that these recommendations are based on moderate quality evidence, and screening programs should only be implemented when appropriate follow-up with high-resolution anoscopy and biopsy capabilities are available.