What is the appropriate work-up and treatment for a patient, potentially immunocompromised or pregnant, presenting with vaginal itching and burning, considering possible diagnoses such as yeast infections (candidiasis), bacterial vaginosis, trichomoniasis, and vulvar dermatitis?

Work-up for Vaginal Itching and Burning

Perform immediate point-of-care testing with vaginal pH measurement, saline wet mount microscopy, and 10% KOH preparation to differentiate between the three most common causes: bacterial vaginosis, vulvovaginal candidiasis, and trichomoniasis. 1

Initial Diagnostic Approach

Essential Point-of-Care Tests

• Measure vaginal pH using narrow-range pH paper as the critical first step to narrow your differential diagnosis 1, 2:

  • pH ≤4.5 indicates vulvovaginal candidiasis 3
  • pH >4.5 suggests bacterial vaginosis or trichomoniasis 1, 2

• Perform saline wet mount microscopy immediately to identify 1, 2:

  • Motile trichomonads (trichomoniasis)
  • Clue cells (bacterial vaginosis)
  • White blood cells indicating inflammation

• Perform 10% KOH preparation to visualize yeast or pseudohyphae confirming candidiasis, and simultaneously conduct the whiff test for fishy odor 3, 1

When to Order Additional Testing

• Obtain vaginal culture if microscopy is negative but symptoms persist, or if recurrent infections are suspected 2
• Order urinalysis to rule out urinary tract infection, especially when dysuria is present 2
• Use nucleic acid amplification testing (NAAT) for trichomoniasis in symptomatic or high-risk women, as wet mount has high false-negative rates 4, 5

Diagnosis by Clinical Presentation

Vulvovaginal Candidiasis (Most Likely with Itching/Burning)

Clinical features:

• Intense vulvar itching and burning are the hallmark symptoms 3, 1
• White, thick "cottage cheese-like" discharge 3, 6
• Vulvovaginal erythema and swelling 3
• Normal vaginal pH (≤4.5) 3
• Affects 75% of women at least once in their lifetime 3, 7

Diagnostic confirmation:

• Yeast or pseudohyphae visible on KOH preparation 3, 1
• Note: 10-20% of asymptomatic women harbor Candida—do not treat colonization without symptoms 3

Bacterial Vaginosis

Clinical features:

• Thin, homogeneous white or gray discharge 3, 8
• Fishy odor, especially after intercourse 3, 8
• Minimal to no vulvar irritation 3
• Accounts for 40-50% of vaginitis cases when cause is identified 4

Diagnostic confirmation using Amsel criteria (3 of 4 required): 3, 4

• Thin homogeneous discharge
• pH >4.5
• Positive whiff test (fishy odor with KOH)
• Clue cells on wet mount

Trichomoniasis

Clinical features:

• Yellow-green, frothy, malodorous discharge 3, 2
• Vulvar irritation and mild pruritus 3, 8
• Vaginal inflammatory changes in most affected women 5

Diagnostic confirmation:

• Motile trichomonads on saline wet mount 3, 1
• NAAT or antigen testing (more sensitive than wet mount) 4, 7

Treatment Algorithms

For Uncomplicated Vulvovaginal Candidiasis

First-line treatment options (equally effective): 3

• Oral fluconazole 150 mg single dose (achieves 55% therapeutic cure rate) 3, 6
• Topical azoles for 1-7 days:
  • Clotrimazole 1% cream 5g intravaginally for 7 days 3
  • Miconazole 2% cream 5g intravaginally for 7 days 3
  • Terconazole 0.4% cream 5g intravaginally for 7 days 3

Follow-up: Return only if symptoms persist or recur within 2 months 3

For Complicated/Recurrent Vulvovaginal Candidiasis (≥4 episodes/year)

Initial extended treatment: 3, 1

• Topical azole therapy for 7-14 days, OR
• Fluconazole 150 mg every 72 hours for 3 doses 1

Maintenance regimen after achieving remission: 3, 1

• Fluconazole 150 mg weekly for 6 months 1, 7
• Alternative: Clotrimazole 500 mg vaginal suppository weekly 3

For Bacterial Vaginosis

Recommended treatment: 3, 4, 7

• Oral metronidazole 500 mg twice daily for 7 days (first-line)
• Alternatives: Intravaginal metronidazole gel or clindamycin cream 3

Follow-up: Unnecessary if symptoms resolve; recurrence is common and requires retreatment 3

For Trichomoniasis

Recommended treatment: 3, 2, 7

• Oral metronidazole 2g single dose (90-95% cure rate)
• Alternative: Metronidazole 500 mg twice daily for 7 days (equal efficacy) 7
• Treat sexual partners simultaneously to prevent reinfection 3, 2

Follow-up: Test of cure is not recommended if symptoms resolve 7

Special Population Considerations

Pregnant Women

• All symptomatic pregnant women with bacterial vaginosis or trichomoniasis must be treated to reduce risk of preterm labor, premature rupture of membranes, and preterm birth 3, 7
• For candidiasis: Use only 7-day topical azole therapy—oral fluconazole is contraindicated in pregnancy 3, 1, 6
• For bacterial vaginosis: Oral metronidazole or clindamycin are acceptable 3
• For trichomoniasis: Oral metronidazole is warranted for prevention of preterm birth 7
• Follow-up evaluation one month after treatment to verify cure 3, 2

Immunocompromised/HIV-Infected Women

• Treat with identical regimens as immunocompetent women—no modification needed 3, 1
• Expected cure rates are equivalent 1
• Consider complicated candidiasis classification if recurrent infections occur 3

Women with Concurrent Infections

• Treat both infections simultaneously when bacterial vaginosis and candidiasis coexist 1
• Use oral metronidazole 500 mg twice daily for 7 days PLUS either oral fluconazole 150 mg or 7-day topical azole 1
• Critical caveat: Metronidazole treatment precipitates vulvovaginal candidiasis in 12.5-30% of patients, making concurrent antifungal therapy essential 1

Common Pitfalls to Avoid

• Do not treat asymptomatic Candida colonization—present in 10-20% of women without requiring treatment 3, 9
• Do not recommend self-medication with OTC antifungals except for women previously diagnosed with candidiasis experiencing identical symptoms 3, 9
• Do not treat male partners for candidiasis routinely—only if symptomatic balanitis is present 1
• Do not use oral fluconazole in pregnancy—teratogenic risk requires topical therapy only 3, 6
• Do not fail to extend initial treatment duration for complicated candidiasis—short courses lead to treatment failure 3, 1
• Do not omit maintenance regimens for recurrent candidiasis—6-month suppression is essential for long-term control 3, 1
• Avoid vaginal douching—disrupts normal flora and increases infection risk 9