| Parameter | Normal findings | Vulvovaginal candidiasis | Bacterial vaginosis | Trichomoniasis |
| Symptoms | None or mild, transient | Pruritus, soreness, dyspareunia | Malodorous discharge, no dyspareunia | Malodorous discharge, burning, postcoital bleeding, dyspareunia, dysuria |
| Signs | Normal vaginal discharge consists of 1 to 4 mL fluid (per 24 hours), which is white or transparent, thin or thick, and mostly odorless | Vulvar erythema and/or edema Discharge may be white and clumpy and may or may not adhere to vagina | Off-white/gray thin discharge that coats the vagina | Thin green-yellow discharge, vulvovaginal erythema |
| Vaginal pH | 4.0 to 4.5 | 4.0 to 4.5 | >4.5 | 5.0 to 6.0* |
| Amine test | Negative | Negative | Positive (in 70 to 80% of patients) | Often positive |
| Saline microscopy | PMN:EC ratio <1; rods dominate; squames +++ | PMN:EC ratio <1; rods dominate; squames +++; pseudohyphae (present in approximately 40% of patients); budding yeast for nonalbicans Candida | PMN:EC <1; loss of rods; increased coccobacilli; clue cells comprise at least 20% of epithelial cells (present in >90% of patients) | PMN ++++; mixed flora; motile trichomonads (present in approximately 60% of patients) |
| 10% potassium hydroxide microscopy | Negative | Pseudohyphae (in approximately 70% of patients) | Negative | Negative |
| Other tests | – | If microscopy nondiagnostic:
| Quantitative microscopy (eg, Nugent criteria, Hay/Ison criteria) Nucleic acid amplification test DNA hybridization probe Culture of no value | If microscopy nondiagnostic:
|
| Differential diagnosis | Physiologic leukorrhea | Contact irritant or allergic vulvar dermatitis, chemical irritation, focal vulvitis (vulvodynia) | Elevated pH in trichomoniasis, atrophic vaginitis, and desquamative inflammatory vaginitis | Purulent vaginitis, desquamative inflammatory vaginitis, atrophic vaginitis, erosive lichen planus |
PMN: polymorphonuclear leukocytes; EC: vaginal epithelial cells.
* In some cases vaginal pH can be normal.