Diagnosis of bacterial vaginosis is made on the basis of Amsel criteria. According to this criteria bacterial vaginosis is present if 3 of the following findings are present: 1) Elevated vaginal pH more than 4.5 2) Positive amine odor when vaginal fluid is mixed with 10% KOH - WHIFF TEST 3) Presence of clue cells (squamous epithelial cells covered with adherent bacteria) in a saline preparation of vaginal fluid 4) Homogenous vaginal discharge In bacterial vaginosis, lactobacilli producing strains are greatly diminished and are replaced with large number of Gardnerella vaginalis. Decline in lactobacilli which normally produce lactic acid, result in increased vaginal pH. This increase in pH allows overgrowth of anaerobic bacteria. Ref: CURRENT Diagnosis & Treatment of Sexually Transmitted Diseases, chapter 11