Can You Perform a Pap Smear During Menstruation?
If a woman is menstruating, a conventional cytology Pap test should be postponed, and the woman should be advised to have a Pap test at the earliest opportunity. 1
Guideline Recommendations
The CDC explicitly states that Pap smears should be rescheduled when a woman is menstruating 1, 2, 3. However, this recommendation comes with important clinical nuances:
When to Postpone vs. Proceed
- Routine screening during normal menses should be postponed to optimize specimen quality and diagnostic accuracy 1, 2
- Do NOT defer screening in cases of abnormal bleeding, including:
- Bleeding between periods
- Post-coital bleeding
- Postmenopausal bleeding 1
- Do NOT postpone if patient accessibility for return examination is difficult 1
The rationale is straightforward: menstrual blood interferes with cytologic interpretation, particularly for conventional Pap smears 1.
Evidence on Diagnostic Performance
Research supports the guideline recommendations:
- During the first 4 days of menstruation, only 80% of smears are of sufficient quality for cytologic diagnosis, meaning 20% are unsatisfactory 4
- A 2025 study comparing Pap smears during proliferative versus secretory phases found no significant difference in diagnostic performance when menstruation itself was not present 5
- The high rate of unsatisfactory specimens during active menstruation is the primary concern 4
Liquid-Based vs. Conventional Cytology
While the guidelines primarily address conventional cytology, the recommendation to postpone during menstruation applies to both collection methods 1. Liquid-based cytology may handle blood contamination slightly better, but postponement remains the standard recommendation 1.
Common Clinical Pitfalls to Avoid
- Do NOT postpone screening for abnormal bleeding patterns - these require immediate evaluation regardless of timing 1
- Do NOT let mucopurulent discharge delay the test - this can be carefully removed with a saline-soaked cotton swab before specimen collection 1, 2, 3
- Do NOT assume women with external genital warts need more frequent screening - they follow standard screening intervals 1, 2, 3
Practical Algorithm
- Is the patient having normal menstrual bleeding? → Reschedule for earliest opportunity after menses 1, 2
- Is the bleeding abnormal (intermenstrual, post-coital, postmenopausal)? → Proceed with Pap smear immediately 1
- Is patient access/follow-up difficult? → Proceed with Pap smear despite menses 1
- Is mucopurulent discharge present? → Remove with saline-soaked swab and proceed 1, 2, 3