Bacterial vaginosis


Clinical Features

  • Whitish-gray vaginal discharge and odor
    • Lack of discharge makes diagnosis less likely
  • May have history of "physiologic whiff test" after contact with male ejaculate which is alkaline (like KOH)

Differential Diagnosis




A "clue cell": note effacement of borders by bacteria, as compared to normal epithelial cells below.
Normal vaginal epithelial cells on wet mount: note clean borders. Presence of lactobacilli (tiny rods) is normal.
  • Wet mount shows clue cells: vaginal epithelial cells with "stippled appearance" due to coverage by bacteria
  • Whiff Test: fishy odor with 10% KOH prep
  • CDC recommends testing all women with BV for HIV and other STDs [1]


Amsel criteria (3/4 must be present)

  • Homogeneous, thin, gray-white discharge
  • Positive whiff test
  • Vaginal pH>4.5
  • Clue cells on wet mount (at least 20% of epithelial cells)


  • No need to treat if asymptomatic
    • In pregnant patients, consider treating to prevent preterm birth, though evidence is conflicting[2]
  • Do NOT need to treat sexual partner


First Line Therapy[3]

  • Metronidazole 500 mg PO BID for 7 days OR
  • Metronidazole gel 0.75%, one full applicator (5 g) intravaginally, qd for 5 days OR
  • Clindamycin cream 2%, one full applicator (5 g) intravaginally qHS for 7 days

Alternative Regimin

  • Tinidazole 2 g PO qd for 2 days OR
  • Tinidazole 1 g PO qd for 5 days OR
  • Clindamycin 300 mg PO BID for 7 days OR
  • Clindamycin ovules 100 mg intravaginally qHS for 3 days (do not use if patient has used latex condom in last 72 hrs)


Prophylaxis (Sexual Assault)


  • Discharge

See Also


  1. 1.0 1.1 1.2 1.3 CDC Pregnancy BV Treatment
  2. Cochrane Database of Systemic REviews. January 2013. Antibiotics for treating bacterial vaginosis in pregnancy.
  3. Workoski KA and Bolan GA. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recommen and Reports. 2015; 64(3):1-140.