Differential Diagnosis for Vulvovaginal Candidiasis
The symptoms of vulvovaginal candidiasis are nonspecific, and before treating empirically, you must confirm the diagnosis with wet mount microscopy showing yeast/hyphae and normal vaginal pH (<4.5), as these symptoms can result from multiple infectious and noninfectious etiologies. 1
Key Diagnostic Principle
The critical issue is that symptoms such as pruritus, vaginal discharge, irritation, soreness, external dysuria, and dyspareunia are not specific for VVC and can be caused by various other conditions. 1 Clinical diagnosis alone leads to misdiagnosis in over 50% of cases, with less than half of patients treated for VVC actually having an objective diagnosis. 1
Differential Diagnoses to Consider
Infectious Causes
Bacterial vaginosis: Distinguished by elevated vaginal pH (>4.5), fishy odor with KOH ("whiff test"), and clue cells on microscopy 1
Trichomoniasis: Presents with elevated vaginal pH (>4.5), frothy discharge, and motile trichomonads on wet mount; affects approximately 75% of women at least once in their lifetime 1
Other sexually transmitted infections: VVC can occur concomitantly with STDs, so their presence doesn't exclude candidiasis 1
Non-albicans Candida species: C. glabrata, C. krusei, C. tropicalis, and C. parapsilosis can cause similar symptoms but may require different treatment approaches 1
Noninfectious Causes
Contact dermatitis: From soaps, detergents, feminine hygiene products, or latex 1
Lichen sclerosus: Chronic inflammatory condition causing vulvar itching and white plaques 2
Lichen planus: Erosive vulvovaginal disease with erythema and discharge 2
Atrophic vaginitis: Particularly in postmenopausal women with estrogen deficiency 2
Cutaneous candidiasis: Estrogen-independent condition distinct from VVC, occurring in different patient populations with different pathogenesis 2
Essential Diagnostic Workup
Before initiating antifungal therapy, perform these specific tests: 1
Vaginal pH measurement: VVC is associated with pH <4.5; elevated pH suggests bacterial vaginosis or trichomoniasis 1
Wet mount with saline and 10% KOH: Look for yeast, pseudohyphae, or hyphae; KOH disrupts cellular material to improve visualization 1
Vaginal culture for Candida: Mandatory if wet mount is negative but clinical suspicion remains high, or in cases of recurrent symptoms 1
Consider molecular testing (PCR): Has superior sensitivity (90.9%) and specificity (94.1%) compared to clinical microscopy (sensitivity 57.5%, specificity 89.4%) for the Candida group 1
Critical Pitfalls to Avoid
Do not treat based on symptoms alone. 1 Approximately 10-20% of asymptomatic women harbor Candida species in the vagina, so identifying Candida by culture without symptoms is not an indication for treatment. 1
Recognize that microscopy has only 61% sensitivity, meaning negative microscopy does not rule out VVC—culture is required. 3
Be aware that self-diagnosis and over-the-counter treatment lead to frequent misdiagnosis, resulting in ineffective treatment and incomplete infection resolution. 4
Treatment Approach Based on Confirmed Diagnosis
For Uncomplicated VVC (90% of cases)
A single 150 mg oral dose of fluconazole is the recommended treatment, achieving >90% response rates. 1, 5 Alternatively, any topical azole agent for 1-7 days is equally effective, with no agent clearly superior. 1
For Complicated VVC (10% of cases)
Defined as severe disease, recurrent episodes (≥3-4 per year), non-albicans species, or infection in immunocompromised hosts. 1 Requires either topical therapy for 5-7 days or fluconazole 150 mg every 72 hours for 3 doses. 1
For C. glabrata Infections
Azole therapy frequently fails. 1 Use topical boric acid 600 mg intravaginally daily for 14 days as first-line alternative, or nystatin suppositories 100,000 units daily for 14 days. 1
For Recurrent VVC
After 10-14 days of induction therapy with topical or oral azole, prescribe fluconazole 150 mg weekly for 6 months, which achieves symptom control in >90% of patients. 1 However, 40-50% of patients experience recurrence after stopping maintenance therapy. 1