What are the symptoms and treatment options for bacterial vaginosis (BV)?

Bacterial Vaginosis: Symptoms and Clinical Presentation

Bacterial vaginosis presents with a characteristic thin, homogeneous white vaginal discharge with a fishy odor, elevated vaginal pH >4.5, and clue cells on microscopy—but up to 50% of women meeting diagnostic criteria are completely asymptomatic. 1, 2

Key Clinical Symptoms

Symptomatic Presentation

• Vaginal discharge: Thin, homogeneous, white, non-inflammatory discharge that smoothly coats the vaginal walls 1, 3
• Fishy odor: Characteristic musty or fishy smell, particularly noticeable after intercourse or during menstruation 1, 4
• Minimal irritation: Unlike candidiasis or trichomoniasis, BV typically does NOT cause significant vulvar itching, burning, or inflammation 1, 2

Asymptomatic Disease

• 50% of cases are silent: Half of women who meet clinical diagnostic criteria report no symptoms whatsoever 1, 2, 5
• This is a critical pitfall—never assume absence of symptoms means absence of disease, especially before invasive procedures 3, 5

Diagnostic Criteria (Amsel Criteria)

Diagnosis requires 3 out of 4 of the following findings: 1, 3

1. Homogeneous white discharge that adheres to vaginal walls
2. Clue cells present on microscopic examination (epithelial cells with adherent bacteria)
3. Vaginal pH >4.5 (use narrow-range pH paper)
4. Positive whiff test: Fishy amine odor when 10% KOH is added to vaginal discharge

Alternative Diagnostic Method

• Gram stain with Nugent scoring: Determines relative concentration of bacterial morphotypes; score ≥4 indicates BV 6
• Culture of Gardnerella vaginalis is NOT recommended—it lacks specificity as this organism is present in 50% of normal women 1

Underlying Pathophysiology

BV results from replacement of normal hydrogen peroxide-producing Lactobacillus species with high concentrations of anaerobic bacteria (Prevotella, Mobiluncus, Bacteroides), Gardnerella vaginalis, and Mycoplasma hominis. 1, 2, 5

Treatment Approach

Who Requires Treatment

Only symptomatic women require treatment for symptom relief. 1, 3 However, there are critical exceptions:

Mandatory Treatment (Even if Asymptomatic):

• Before surgical abortion: Metronidazole substantially reduces post-abortion PID 1, 3
• Before hysterectomy or invasive gynecological procedures: Reduces risk of postoperative infectious complications 3
• High-risk pregnant women with history of preterm delivery 3

First-Line Treatment Regimens

Metronidazole 500 mg orally twice daily for 7 days is the preferred regimen with 95% cure rate. 3 Alternative options include:

• Metronidazole gel 0.75%: One full applicator (5g) intravaginally once daily for 5 days 3
• Clindamycin cream 2%: One full applicator (5g) intravaginally at bedtime for 7 days 3
• Metronidazole 2g orally single dose: 84% cure rate; useful when compliance is a concern 3
• Tinidazole 2g once daily for 2 days OR 1g once daily for 5 days: FDA-approved alternative 6
• Clindamycin 300 mg orally twice daily for 7 days 3

Critical Treatment Warnings

• Avoid alcohol during metronidazole or tinidazole treatment and for 24 hours after completion due to disulfiram-like reaction 3
• Clindamycin cream is oil-based and weakens latex condoms and diaphragms 3
• Do NOT treat male sexual partners—this has not been shown to prevent recurrence or alter clinical course 1, 3, 5

Recurrence and Long-Term Management

50-80% of women experience BV recurrence within one year of antibiotic treatment. 7, 8 For recurrent BV:

• Extended metronidazole 500 mg twice daily for 10-14 days 8
• If ineffective: Metronidazole gel 0.75% for 10 days, then twice weekly for 3-6 months 8
• Probiotics containing Lactobacillus species as complementary therapy significantly improve cure rates (RR 1.53,95% CI 1.19-1.97) when combined with antibiotics 2, 5

Common Clinical Pitfalls to Avoid

• Assuming all BV is symptomatic: 50% of cases are asymptomatic—screen before invasive procedures 3, 5
• Treating sexual partners: This does not prevent recurrence and wastes resources 1, 3, 5
• Using G. vaginalis culture for diagnosis: Lacks specificity 1
• Failing to treat before abortion or hysterectomy: Substantially increases risk of post-procedure PID and infectious complications 1, 3
• Confusing BV with candidiasis: BV lacks significant vulvar inflammation and itching 1, 2