What is the diagnosis and treatment for a patient with Clue cells present in a wet prep?

Diagnosis and Treatment of Bacterial Vaginosis Based on Clue Cells in Wet Prep

The presence of clue cells on wet mount examination is diagnostic of bacterial vaginosis (BV) and should be treated with metronidazole 500 mg orally twice daily for 7 days as first-line therapy. 1, 2

Diagnosis of Bacterial Vaginosis

Diagnostic Criteria

• BV diagnosis requires meeting at least 3 of 4 Amsel criteria:

  • Homogeneous, white, non-inflammatory discharge that smoothly coats the vaginal walls 1
  • Presence of clue cells on microscopic examination 1
  • Vaginal pH greater than 4.5 1
  • Fishy odor of vaginal discharge before or after addition of 10% KOH (positive whiff test) 1

• Clue cells are epithelial cells heavily covered with adherent bacteria, typically Gardnerella vaginalis, and are the single most reliable indicator of BV (sensitivity 98.2%, specificity 94.3%) 3

• True clue cells show direct cohesive adherence of bacteria to epithelial cells, which is unique for Gardnerella species 4

• Wet mount examination should be performed as soon as possible after collection to increase the likelihood of detecting organisms 1

Laboratory Methods

• Microscopic examination of vaginal discharge with saline wet mount is the most practical method for diagnosing BV in the office setting 1

• Gram stain of vaginal smear is an acceptable laboratory method with high specificity (95%) but moderate sensitivity (62%) 1, 5

• Culture for G. vaginalis is not recommended as a diagnostic tool because it is not specific (positive predictive value only 41%) 1, 5, 6

Treatment Recommendations

First-Line Treatment

• Metronidazole 500 mg orally twice daily for 7 days (95% cure rate) 1, 2

• Patients should be advised to avoid alcohol during treatment with metronidazole and for 24 hours afterward due to potential disulfiram-like reaction 1

Alternative Regimens

• Metronidazole 2 g orally in a single dose (84% cure rate) - useful when compliance is a concern 1, 2

• Tinidazole 2 g once daily for 2 days or 1 g once daily for 5 days - demonstrated superior efficacy over placebo in clinical trials 7

• Metronidazole gel 0.75%, one full applicator (5g) intravaginally once daily for 5 days 2

• Clindamycin cream 2%, one full applicator (5g) intravaginally at bedtime for 7 days 2

Special Considerations

Pregnancy

• BV during pregnancy is associated with adverse pregnancy outcomes including preterm delivery 1

• Treatment of pregnant women with BV who are at high risk for preterm delivery (previous preterm birth) may reduce the risk for prematurity 1

• The U.S. Preventive Services Task Force recommends against routinely screening average-risk asymptomatic pregnant women for BV 1

Invasive Procedures

• Consider treating BV before invasive gynecological procedures such as endometrial biopsy, hysterectomy, or abortion to reduce risk of post-procedure infections 1, 2

• Treatment of BV with metronidazole has been shown to substantially reduce post-abortion pelvic inflammatory disease (PID) 1

Clinical Pitfalls to Avoid

• Failing to examine wet mount promptly may decrease sensitivity for detecting organisms 1

• Treating asymptomatic women unnecessarily exposes them to medication side effects without clear benefit, except in specific high-risk scenarios 1, 2

• Treatment of male sex partners has not been shown to alter the clinical course or reduce recurrence rates of BV and is not recommended 1

• Clindamycin cream is oil-based and might weaken latex condoms and diaphragms during treatment and for 5 days after therapy 2

• Laboratory testing fails to identify the cause of vaginitis in a substantial minority of women; consider other causes if treatment fails 1