What is the likely diagnosis and recommended treatment for a woman with white or gray‑white vaginal discharge and a fishy odor who denies recent sexual contact?

White Vaginal Discharge with Fishy Smell: Bacterial Vaginosis

This presentation is bacterial vaginosis (BV), and you should treat with oral metronidazole 500 mg twice daily for 7 days, which achieves a 95% cure rate. 1, 2

Diagnosis

The combination of white discharge and fishy odor makes BV the most likely diagnosis, even without sexual contact. 3 BV is not exclusively a sexually transmitted disease—women who have never been sexually active can be affected, though it is less common. 3

Confirm the diagnosis using Amsel criteria (need 3 of 4): 3, 2

• Homogeneous white discharge coating the vaginal walls
• Clue cells on saline wet-mount microscopy
• Vaginal pH > 4.5
• Positive whiff test (fishy odor with 10% KOH)

Bedside Testing

• Perform saline wet-mount microscopy immediately to identify clue cells 1
• Measure vaginal pH with litmus paper; pH > 4.5 favors BV (pH < 4.5 suggests candidiasis instead) 1
• Apply 10% KOH to the discharge—an immediate fishy amine odor confirms a positive whiff test 3

Critical pitfall: Do not order culture for Gardnerella vaginalis—it lacks specificity because this organism is isolated from 50% of normal asymptomatic women. 3, 2, 4

Treatment Regimen

First-Line Therapy

Metronidazole 500 mg orally twice daily for 7 days 1, 2, 4

• This achieves approximately 95% cure rate 1, 2
• Instruct the patient to avoid all alcohol during treatment and for 24 hours after completion to prevent a disulfiram-like reaction 1, 2, 4

Alternative Regimens (if oral therapy is not tolerated)

• Metronidazole gel 0.75% intravaginally once daily for 5 days 1, 2
• Clindamycin cream 2% intravaginally at bedtime for 7 days 1, 2
  • Warning: Clindamycin cream is oil-based and weakens latex condoms and diaphragms 2

Avoid single-dose metronidazole 2 g—cure rates are lower at 84% versus 95% for the 7-day regimen. 1, 2

Partner Management

Do not treat sexual partners. 3, 2, 4 Treatment of male partners has not been shown to prevent recurrence or alter the clinical course in women, according to CDC guidelines. 3, 2 The absence of sexual contact in this case further supports that partner treatment is unnecessary.

Follow-Up and Recurrence

• No routine follow-up is needed if symptoms resolve 4
• Recurrence is common: 50–80% of women experience recurrence within one year 1, 4, 5
• If symptoms return, repeat evaluation with the same diagnostic approach is needed 1
• For recurrent BV (≥3 episodes per year), consider extended metronidazole therapy: 500 mg twice daily for 10–14 days, followed by metronidazole gel 0.75% twice weekly for 3–6 months 5

Important Clinical Context

Why Treat Symptomatic BV

The principal goal is to relieve vaginal symptoms and signs. 3, 2 Only symptomatic women require treatment. 3, 2, 4

However, BV also increases risk of: 3, 2

• Pelvic inflammatory disease
• Endometritis
• Vaginal cuff cellulitis after invasive gynecologic procedures

Therefore, treat BV before: 1, 2

• Surgical abortion
• Hysterectomy
• IUD insertion
• Other invasive gynecologic procedures

This markedly reduces post-procedure pelvic inflammatory disease risk. 1, 2

Asymptomatic BV

Up to 50% of women meeting diagnostic criteria for BV are asymptomatic. 3, 2 If this patient had no symptoms and BV was found incidentally, treatment would not be indicated unless she were pregnant with high preterm delivery risk or scheduled for an invasive procedure. 2, 4