Should a Pap smear be performed on a patient with an untreated Trichomonas (trichomoniasis) infection?

Pap Smear in Untreated Trichomonas Infection

Yes, perform the Pap smear even with untreated trichomonas—the presence of infection should not delay cervical cancer screening. 1, 2

Primary Guideline Recommendation

The CDC explicitly states that mucopurulent discharge or vaginal infection should not postpone cytology testing, and the test can be performed after careful removal of the discharge with a saline-soaked cotton swab. 1, 2 This recommendation applies directly to trichomonas and other cervical infections. 2

Practical Collection Technique

• Remove visible discharge first using a saline-soaked cotton swab to gently clear mucopurulent or excessive discharge from the cervix before collecting the Pap specimen. 1, 2
• Proceed with standard collection using an extended-tip spatula for the ectocervix and endocervical brush for the endocervical canal. 2
• Even in the presence of severe cervical infections, Pap tests will typically be reported as satisfactory for evaluation, and reliable final reports can be produced without repeating the test after treatment. 1, 2

Type of Cytology Matters

• Liquid-based cytology is preferred as it can be performed at any time and produces fewer inadequate specimens and false-negative results compared to conventional cytology. 2, 3
• Conventional cytology may be more affected by heavy discharge but remains acceptable if liquid-based cytology is unavailable. 2

Important Clinical Context

Why This Matters for Patient Care

• The FDA label for metronidazole explicitly states that trichomonas can interfere with accurate assessment of abnormal cytological smears, and additional smears should be performed after eradication of the parasite. 4
• This means you should perform the Pap smear now (don't delay screening), but plan to repeat it after treating the infection if any abnormalities are detected. 4
• Research demonstrates that Pap smears can detect asymptomatic trichomonas in 16-38% of cases that would otherwise be missed. 5, 6

When to Repeat After Treatment

• If the initial Pap smear shows ASCUS with severe inflammation and trichomonas, treat the infection and repeat the Pap smear 2-3 months after appropriate treatment. 7
• If inflammation persists without identified infection on repeat testing, perform Pap smears every 4-6 months for 2 years until three consecutive negative results. 7

Critical Exceptions—When NOT to Delay

• Never postpone screening if the patient has abnormal bleeding (intermenstrual, post-coital, or postmenopausal bleeding). 2
• Never postpone screening if there are accessibility issues where return examination is difficult or patient compliance concerns. 2
• Never postpone screening simply because discharge is present—this is a common pitfall. 1, 2

Common Pitfalls to Avoid

• Do not cancel the Pap appointment simply because the patient has vaginal discharge or diagnosed trichomonas. 2
• Do not assume an "unsatisfactory" result is inevitable—most Pap tests remain satisfactory even with concurrent infections. 1, 2
• Do not rely on Pap smear alone to diagnose or screen for trichomonas—it is not a screening test for STDs, though it can incidentally detect the organism. 1, 7
• Do not skip follow-up—if trichomonas is detected on Pap smear, the patient requires treatment with metronidazole and consideration of repeat cytology after treatment. 4, 8

Clinical Algorithm

1. Proceed with Pap smear regardless of untreated trichomonas
2. Remove visible discharge with saline-soaked cotton swab before collection 1, 2
3. Collect specimen using standard technique 2
4. Treat trichomonas with metronidazole per FDA indication 4
5. Repeat Pap smear in 2-3 months if initial smear shows ASCUS with inflammation 7
6. Resume routine screening intervals if repeat smear is normal 7