Do we treat bacterial vaginosis (BV) in pregnancy?

Treatment of Bacterial Vaginosis in Pregnancy

Yes, treat all symptomatic pregnant women with bacterial vaginosis, but do not routinely screen or treat asymptomatic low-risk pregnant women. 1, 2

Symptomatic Pregnant Women

All pregnant women with symptomatic BV must receive treatment to relieve vaginal discharge and other symptoms, and to potentially reduce adverse pregnancy outcomes including preterm birth, premature rupture of membranes, and postpartum endometritis. 1, 2

Recommended Treatment Regimens

First-line options include:

• Oral metronidazole 500 mg twice daily for 7 days (preferred for systemic coverage of potential upper tract infection) 1, 2
• Oral metronidazole 250 mg three times daily for 7 days (alternative dosing) 3
• Metronidazole gel 0.75%, one applicator (5g) intravaginally once daily for 5 days 1, 2
• Clindamycin cream 2%, one applicator (5g) intravaginally at bedtime for 7 days 1, 2

Critical precautions:

• Patients must avoid alcohol during metronidazole treatment and for 24 hours after completion due to disulfiram-like reaction risk 1, 2
• Oil-based clindamycin preparations may weaken latex condoms and diaphragms 1, 2

Follow-Up Requirements

Perform a follow-up evaluation one month after treatment completion to verify cure, as BV in pregnancy is associated with serious adverse outcomes including preterm delivery and postpartum endometritis. 1, 2 This differs from non-pregnant women where follow-up is unnecessary if symptoms resolve. 1

Asymptomatic Pregnant Women: Risk-Stratified Approach

Low-Risk Women (No Prior Preterm Birth)

Do not routinely screen or treat asymptomatic low-risk pregnant women - there is good evidence that screening and treatment do not improve outcomes such as preterm labor or preterm birth in this population. 1, 2 In fact, some studies show potential harm: women without BV who received treatment experienced trends toward higher rates of preterm delivery before 34 weeks (12-13% versus 4-5%) and increased neonatal sepsis with vaginal clindamycin. 1

High-Risk Women (Prior Preterm Delivery)

Consider screening and treating asymptomatic high-risk women with a history of prior preterm delivery, as treatment may reduce the risk of recurrent preterm birth. 1, 2 However, the evidence is mixed and conflicting:

• Three trials in very high-risk populations (35-57% baseline preterm delivery rate) showed benefit, with oral metronidazole reducing preterm delivery before 37 weeks. 1
• A large multicenter American trial (1999) showed no benefit of oral metronidazole in women with previous preterm delivery. 1
• The heterogeneity in results suggests that a single previous preterm delivery alone may not reliably identify women who will benefit. 1

If screening high-risk women:

• Screen in the second trimester (13-24 weeks gestation) when benefit was demonstrated in positive trials 1
• Use oral metronidazole (with or without erythromycin) rather than vaginal preparations for potential subclinical upper tract infection 1
• Consider additional risk factors beyond just prior preterm delivery when making the screening decision 1

Diagnostic Criteria

Diagnose BV using clinical criteria (Amsel's criteria) - at least 3 of 4 findings:

• Vaginal pH >4.5 1, 2
• Homogeneous white vaginal discharge 1, 2
• Clue cells on microscopic wet mount examination 1, 2
• Positive whiff test (fishy odor with potassium hydroxide application) 1, 2

Common Pitfalls to Avoid

• Do not treat asymptomatic low-risk women - evidence shows no benefit and potential harm 1, 2
• Do not use single-dose metronidazole 2g in pregnancy - the 7-day regimen is preferred for adequate treatment 1
• Do not skip the one-month follow-up visit in pregnant women, unlike non-pregnant patients 1, 2
• Do not treat male partners - this has not been shown to prevent recurrence or improve outcomes 1

Special Considerations

Women undergoing surgical abortion or cesarean section: Consider screening and treating BV before these procedures, as treatment with metronidazole substantially reduces post-abortion pelvic inflammatory disease and post-operative infectious complications. 1