Basis of diagnosis		Bacterial vaginosis	Vulvovaginal candidiasis	Trichomoniasis
Signs and symptoms		Thin, off-white discharge Unpleasant “fishy” odor, with odor increasing after sexual intercourse	Thick, white (“cottage cheese”) discharge with no odor Pruritus Dysuria	Copious, malodorous, yellow- green (or discolored) discharge Pruritus Vaginal irritation No symptoms in 20 to 50 percent of affected women
Physical examination		Usually, normal appearance of tissue; discolored discharge with abnormal odor, homogeneous discharge that adheres to vaginal walls	Vulvar and vaginal erythema, edema and fissures Thick, white discharge that adheres to vaginal walls	Vulvar and vaginal edema and erythema “Strawberry” cervix in up to 25 percent of affected women Frothy, purulent discharge
Laboratory tests
	Vaginal pH (normal = < 4.5)	Elevated (> 4.5)	Normal	Elevated (> 4.5)
	Microscopic examination of wet-mount and KOH preparations of vaginal discharge	“Clue cells” (vaginal epithelial cells coated with coccobacilli) Few lactobacilli Occasional motile, curved rods (Mobiluncus species)	Pseudohyphae, mycelial tangles or budding yeast cells	Motile trichomonads Many polymorphonuclear cells
	“Whiff” test (normal = no odor)	Positive	Negative	Can be positive
	Additional tests	Amsel's criteria (three of four criteria must be met): provides correct diagnosis in 90 percent of affected women	KOH microscopy Gram stain Culture	DNA probe tests: sensitivity of 90 percent and specificity of 99.8 percent
				Culture: sensitivity of 98 percent and specificity of 100 percent
		Criteria of Nugent or Spiegel for Gram stain to diagnose bacterial vaginosis Other tests are controversial.