What is the treatment for bacterial vaginosis (BV) in women, including those who are pregnant?

Treatment of Bacterial Vaginosis (Gardnerella vaginalis)

For symptomatic non-pregnant women, treat with metronidazole 500 mg orally twice daily for 7 days, which achieves a 95% cure rate and is the CDC's first-line recommendation. 1

Diagnosis Before Treatment

Bacterial vaginosis requires at least 3 of the following 4 Amsel criteria for diagnosis: 1

• Homogeneous white non-inflammatory vaginal discharge
• Clue cells on microscopic examination
• Vaginal pH >4.5
• Positive "whiff test" (fishy odor with 10% KOH)

Alternatively, a Gram stain showing Nugent score ≥4 confirms the diagnosis. 2 Culture of G. vaginalis is not recommended as it lacks specificity. 3

First-Line Treatment Regimens for Non-Pregnant Women

Recommended options (all equally effective): 3, 1

• Metronidazole 500 mg orally twice daily for 7 days - 95% cure rate, most studied regimen 1
• Metronidazole gel 0.75%, one full applicator (5g) intravaginally twice daily for 5 days - 75-84% cure rate 3, 1
• Clindamycin cream 2%, one full applicator (5g) intravaginally at bedtime for 7 days - 78-84% cure rate 3, 1

Alternative Regimens (Lower Efficacy)

Use only when first-line options are not feasible: 3, 1

• Metronidazole 2g orally as single dose - 84% cure rate (lower than 7-day regimen, should not be first-line) 3, 1
• Clindamycin 300 mg orally twice daily for 7 days 3, 1
• Tinidazole 2g once daily for 2 days OR 1g once daily for 5 days - demonstrated superior efficacy over placebo 2

Treatment in Pregnancy

All symptomatic pregnant women require treatment due to associations with preterm birth, premature rupture of membranes, preterm labor, and postpartum endometritis. 4, 1

Preferred regimens for pregnant women (systemic therapy required): 4

• Metronidazole 250 mg orally three times daily for 7 days (CDC first-line) 4
• Clindamycin 300 mg orally twice daily for 7 days (alternative first-line) 4

High-risk pregnant women (history of prior preterm delivery) with asymptomatic BV may be evaluated for treatment, as this has reduced preterm delivery in 3 of 4 randomized trials. 4 Optimal screening time is second trimester (13-24 weeks). 5

Average-risk pregnant women should NOT be routinely screened or treated if asymptomatic, as it does not improve outcomes. 5

Special Clinical Situations Requiring Treatment of Asymptomatic BV

Treatment of asymptomatic BV is indicated before: 5, 1

• Surgical abortion - reduces post-abortion PID substantially 5, 1
• Hysterectomy - reduces postoperative infectious complications by 10-75% 1
• Other invasive gynecological procedures (endometrial biopsy, IUD placement, cesarean section) due to risk of endometritis, PID, and vaginal cuff cellulitis 5

Critical Safety Warnings

Metronidazole precautions: 3, 4, 1

• Patients MUST avoid alcohol during treatment and for 24 hours after completion due to disulfiram-like reaction

Clindamycin cream precautions: 3, 1

• Oil-based formulation may weaken latex condoms and diaphragms

Recurrent Bacterial Vaginosis

50-80% of women experience recurrence within 1 year of treatment. 6, 7

For recurrent BV, use extended therapy: 6

• Metronidazole 500 mg orally twice daily for 10-14 days (first approach)
• If ineffective: Metronidazole gel 0.75% for 10 days, then twice weekly for 3-6 months as suppressive therapy 6

Follow-Up Recommendations

• Non-pregnant women: No follow-up needed if symptoms resolve 1
• Pregnant women (especially high-risk): Follow-up evaluation 1 month after treatment completion to verify cure 5, 4

What NOT to Do

Do NOT treat male sex partners - multiple randomized trials demonstrate this does not prevent recurrence or alter clinical outcomes. 3, 1, 8 Treatment of male partners has shown no benefit in preventing BV recurrence. 3