Synopsis
Diagnose bacterial vaginosis as a vaginal dysbiosis, choose an effective oral or intravaginal regimen, and manage pregnancy and recurrence without unnecessary partner antibiotics.
- Bacterial vaginosis is vaginal dysbiosis with reduced lactobacilli and anaerobic biofilm; it commonly causes thin homogeneous grey-white discharge and fishy odour with little itch or inflammation.
- Confirm with a Gram-stained vaginal smear using Hay–Ison or Nugent criteria, or with at least three of four Amsel criteria when point-of-care assessment is appropriate.
- Vaginal pH above 4.5 supports BV but is not diagnostic because semen, blood and trichomoniasis can also increase pH.
Key red flags
Pelvic pain, fever, cervical motion or adnexal tenderness requires assessment for PID instead of repeated bacterial-vaginosis therapy.
Pregnancy with pain, bleeding, contractions, ruptured membranes or reduced fetal movement needs urgent maternity review.
Persistent blood-stained discharge, ulceration, contact bleeding or a mass requires cervical, vaginal or vulval assessment for neoplasia.
Severe vulval pain, spreading erythema, crepitus or systemic toxicity suggests invasive soft-tissue infection and requires emergency care.
Repeated malodour despite verified diagnosis and treatment should prompt examination for a retained foreign body and alternative infection.
Pelvic pain, fever, cervical motion tenderness or adnexal tenderness indicates possible PID and requires broader urgent treatment.
Investigation priorities
Grade lactobacillus depletion and BV-associated morphotypes using Hay–Ison or Nugent criteria.
Management branches
A patient presents with thin malodorous discharge and little vulval inflammation.
- Ask about odour, itch, pain, bleeding, pregnancy, products, douching, antibiotics, retained material and sexual-health risks.
- Examine when indicated, measure vaginal pH and use Gram stain or Amsel criteria rather than relying on discharge colour alone.