What are the guidelines for Pap (Papanicolau) smear screening for cervical cancer?

Pap Smear Screening Guidelines

Begin cervical cancer screening at age 21 years for all women regardless of sexual activity history, screen women aged 21-29 every 3 years with cytology alone, and screen women aged 30-65 every 5 years with HPV/Pap co-testing (preferred) or every 3 years with cytology alone. 1, 2

When to Start Screening

• Initiate screening at age 21 years for all women, regardless of when sexual activity began or whether they have ever been sexually active. 1, 2
• Do not screen women under age 21 years under any circumstances—cervical cancer incidence is extremely low in this age group (only 0.1% of all cervical cancer cases occur before age 21). 2, 3
• The previous recommendation to begin screening within 3 years of sexual debut has been abandoned because age-based screening is more effective and self-reported sexual history is unreliable. 1

Screening Intervals by Age

Ages 21-29 Years

• Screen every 3 years using conventional or liquid-based Pap cytology alone. 4, 2
• Do not use HPV testing for primary screening in this age group—HPV co-testing is not recommended for women under 30 because HPV infections are extremely common and usually transient in younger women. 4
• Annual screening is explicitly not recommended for any age group. 4

Ages 30-65 Years

• Preferred strategy: Co-testing with both HPV DNA test and Pap cytology every 5 years. 4, 2
• Acceptable alternative: Pap cytology alone every 3 years if co-testing is unavailable. 4, 2
• HPV testing should never be used as a stand-alone screening test. 4
• The 5-year interval with co-testing is safe because the combination provides higher sensitivity for detecting high-grade lesions. 2

When to Stop Screening

• Discontinue screening at age 65 years if a woman has had adequate prior screening with normal results: either ≥3 consecutive negative Pap tests OR ≥2 consecutive negative co-tests within the past 10 years, with the most recent test within the past 5 years. 4, 2
• Women over 65 with recent abnormal results (even HPV-negative ASC-US) should continue screening until they achieve 2 consecutive negative co-tests or 3 consecutive negative Pap tests. 4
• Women who have had a total hysterectomy with removal of the cervix for benign reasons and no history of high-grade precancerous lesions should discontinue screening entirely. 2

Special Populations Requiring Modified Screening

Women with HIV or Immunocompromised Status

• These women require more frequent screening but should still not begin before age 21 years. 1
• Follow CDC-specific guidelines for HIV-infected women rather than standard screening intervals. 4

Women with History of Cervical Cancer or High-Grade Lesions

• Continue surveillance indefinitely—do not stop at age 65. 2
• These women require different follow-up protocols beyond routine screening. 2

Women with DES Exposure In Utero

• Screen annually due to increased risk of cervical and vaginal cancers. 4

Pregnant Women

• Follow the same screening intervals as non-pregnant women. 4
• Conservative management is recommended for abnormal results—treatment should be deferred until after delivery unless invasive cancer is detected. 4

HPV-Vaccinated Women

• Screen using identical recommendations as unvaccinated women—vaccination does not change screening protocols. 4

Management of Abnormal Results

ASC-US (Atypical Squamous Cells of Undetermined Significance)

• Manage with HPV triage testing—perform colposcopy only if HPV-positive. 4
• If HPV testing is unavailable, repeat Pap test in 1 year is acceptable. 4
• Do not use HPV 16/18 genotyping for ASC-US triage—it does not alter management since colposcopy is indicated regardless. 4

HPV-Positive with Normal Cytology (Ages 30-65)

• If HPV 16 or 18 detected: proceed directly to colposcopy due to higher CIN3+ risk. 4
• If other high-risk HPV types (non-16/18): repeat co-testing in 1 year. 4

Young Women Ages 21-24

• Use conservative management strategies—many high-grade lesions will spontaneously regress in this age group. 4
• Treatment increases risk of preterm delivery in future pregnancies, so observation is often preferred over immediate intervention. 4

Common Pitfalls to Avoid

• Do not screen annually—this increases false positives, unnecessary procedures, and costs without meaningful improvement in cancer prevention (less than 5% benefit compared to 3-year intervals). 2
• Do not screen women under 21—even if sexually active, the cancer risk does not justify screening harms. 1, 3
• Do not use HPV testing alone for primary screening—it must be combined with cytology (co-testing) or used only for triage of abnormal cytology. 4
• Do not continue screening after adequate negative results at age 65+—overscreening in this population causes more harm than benefit. 4
• Be aware that adenocarcinomas may progress more rapidly in women under 30, with mean time from normal Pap to invasive adenocarcinoma being only 15 months versus 56 months in older women—this is a limitation of extended screening intervals in younger women. 5

Rationale for Current Guidelines

• The Pap test has 70-80% sensitivity for high-grade CIN, and false negatives cannot be entirely eliminated even in optimized programs. 4
• Approximately 50% of cervical cancers in the US occur in women who have never been screened, making access to screening more important than screening frequency. 4
• Extended intervals reduce patient harm from overtreatment while maintaining nearly equivalent cancer prevention compared to annual screening. 2
• Co-testing with HPV allows safe extension to 5-year intervals in women 30-65 due to the high negative predictive value of dual-negative results. 4