Do you treat bacterial vaginosis (BV) if rare clue cells are present on a wet prep?

Treatment of Rare Clue Cells on Wet Prep

Do not treat bacterial vaginosis based solely on rare clue cells without meeting full diagnostic criteria—BV requires at least 3 of 4 Amsel criteria, and rare clue cells alone do not constitute a diagnosis. 1

Diagnostic Requirements

The presence of rare clue cells is insufficient for BV diagnosis. You must apply the Amsel criteria systematically:

• BV diagnosis requires meeting at least 3 of the following 4 criteria: homogeneous white discharge adhering to vaginal walls, clue cells on microscopy, vaginal pH >4.5, and positive whiff test (fishy odor with 10% KOH) 1, 2

• Clue cells are defined as vaginal epithelial cells with bacteria adhered to their surface creating a stippled appearance with obscured cell borders—not just any bacteria near epithelial cells 1

• The CDC explicitly warns against diagnosing BV without adequate clue cells unless confirmed by Gram stain, as this leads to treating the wrong condition 1

When Wet Mount Findings Are Equivocal

If you're uncertain whether rare clue cells represent true BV:

• Order a quantitative Gram stain (Nugent criteria), which the CDC recommends as the most specific procedure when wet mount is equivocal 1

• Consider multiplex NAAT panels to detect microbiome-based BV, Candida species, and Trichomonas in a single test 1

• The Infectious Diseases Society of America explicitly recommends against treating asymptomatic patients with incidental bacterial findings and no clue cells 1

Treatment Decision Algorithm

Do NOT Treat If:

• Only rare clue cells present without meeting 3 of 4 Amsel criteria 1, 2
• Patient is asymptomatic with indeterminate results 2
• No planned invasive gynecologic procedures 2

DO Treat Despite Indeterminate Results If:

• Before surgical abortion procedures—metronidazole substantially reduces post-abortion PID 2
• Before hysterectomy or other invasive gynecological procedures—due to increased risk for postoperative infectious complications 2
• High-risk pregnant women with history of preterm delivery—may reduce risk of prematurity 2

Treatment Regimen When Indicated

If you determine treatment is warranted after meeting diagnostic criteria:

• First-line: Metronidazole 500 mg orally twice daily for 7 days (95% cure rate) 2
• Alternative: Metronidazole gel 0.75%, one full applicator intravaginally once daily for 5 days 2
• Single-dose option: Metronidazole 2g orally once (84% cure rate, lower efficacy but useful for compliance concerns) 2

Critical Pitfalls to Avoid

• Do not rely solely on wet mount sensitivity, which is only 40-80% and has significant interpretation variability 1

• Rare clue cells may represent pseudo clue cells—epithelial cells mechanically entrapped in bacterial masses rather than true adherent Gardnerella biofilm, which occurs in 44% of morphologically diagnosed BV cases 3

• Treating asymptomatic women with indeterminate results unnecessarily exposes them to medication side effects without clear benefit 2

• Remember that up to 50% of women with true BV are asymptomatic, but this does not justify treating based on inadequate diagnostic criteria 4

• Warn patients using metronidazole to avoid alcohol during treatment and for 24 hours afterward due to potential disulfiram-like reaction 2