National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention
Division of Sexually Transmitted Diseases
Program and Training Branch
Diagnostic Methods
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Bacterial vaginosis can be diagnosed using the following
Amsel criteria. The presence of three of the following four
criteria provides sufficient evidence for a clinical
diagnosis of BV.
The presence of clue cells (bacterial clumping upon the borders of epithelial cells) on wet mount examination. Clue cells should constitute at least 20% of all epithelial cells (an occasional clue cell does not fulfill this criteria).
Positive amine, "whiff" or "fishy odor" test (liberation of biologic amines with or without the addition of 10% KOH).
Homogeneous, non-viscous, milky-white discharge adherent to the vaginal walls.
Gold standard for diagnosis of BV is vaginal Gram stain to assist in the diagnosis of BV (Nugent or Speigel criteria). A normal Gram stain would show lactobacillus (long Gam-positive rods) only or lactobacillus with gardnerella. When a more mixed flora is present and lactobacillus is absent or present in low numbers, the smear would be interpreted as consistent with BV.
Cultures are not recommended.
DNA probe--Affirm™ V.P. III, can detect high levels of
G. vaginalis.
Other diagnostic modalities include PIP activity and sialidase tests (BVBlue).
These tests detect abnormal pH, high levels of trimethylamine or high levels of
proline aminopeptidase.
