What is the appropriate diagnostic workup and treatment for a patient presenting with yellow vaginal discharge and pruritus?

Diagnostic Workup for Yellow Vaginal Discharge with Pruritus

Initial Diagnostic Tests Required

For a patient presenting with yellow vaginal discharge and pruritus, you should immediately perform vaginal pH measurement, saline wet mount microscopy, and KOH preparation at the point of care. 1, 2

Essential Point-of-Care Tests

• Vaginal pH measurement using narrow-range pH paper applied directly to vaginal secretions is the critical first step to narrow your differential 2

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

• Saline wet mount microscopy should be examined immediately to identify:

  • Motile trichomonads (trichomoniasis) - the most likely diagnosis given yellow discharge 1, 2
  • Clue cells (bacterial vaginosis) 1
  • White blood cells indicating inflammation 3

• KOH 10% preparation to identify:

  • Yeast or pseudohyphae (candidiasis) - relevant given the pruritus 1, 2
  • Perform whiff test simultaneously (fishy odor indicates bacterial vaginosis or trichomoniasis) 2

Additional Laboratory Tests

• Gram stain of vaginal discharge can confirm bacterial vaginosis through Nugent scoring and identify bacterial pathogens 4

• Vaginal culture should be obtained if:

  • Microscopy is negative but symptoms persist 4
  • Recurrent infections are suspected 3
  • Treatment failure occurs 3

• Urinalysis is indicated to rule out urinary tract infection, especially if the patient reports dysuria 3

Most Likely Diagnoses Based on Presentation

Trichomoniasis (Primary Consideration)

Yellow discharge strongly suggests trichomoniasis, which characteristically presents with yellow-green discharge, malodor, and vulvar irritation. 3, 5

• Diagnosis requires identification of motile trichomonads on wet mount 5
• This is a sexually transmitted infection requiring partner treatment 3, 2
• Treatment: Metronidazole 2 grams orally as single dose (90-95% cure rate) 3, 2

Vulvovaginal Candidiasis (Secondary Consideration)

The pruritus component suggests possible candidiasis, though yellow discharge is atypical 3

• Candidiasis typically presents with white "cottage cheese-like" discharge and intense pruritus 3, 6
• Diagnosis confirmed by yeast/pseudohyphae on KOH preparation 1
• Treatment: Fluconazole 150 mg orally as single dose (55% therapeutic cure rate) 2, 7

Mixed Infection Possibility

• Approximately 10-20% of women harbor Candida asymptomatically, so concurrent infections can occur 3, 5
• Yellow discharge with pruritus may represent trichomoniasis with secondary candidal colonization 4

Common Pitfalls to Avoid

• Do not treat empirically without microscopy - the three common causes (bacterial vaginosis, candidiasis, trichomoniasis) require different treatments 1, 4

• Do not rely on clinical appearance alone - symptoms and discharge characteristics overlap significantly between conditions 8

• Do not treat asymptomatic Candida colonization found incidentally on testing 5

• Do not forget partner treatment for trichomoniasis - failure to treat partners leads to reinfection 3, 2

Tests NOT Routinely Needed

• Cervical testing for gonorrhea/chlamydia should only be added if:

  • Patient has cervical motion tenderness, suggesting pelvic inflammatory disease 3
  • Patient is at high risk for STIs with multiple partners 3
  • Mucopurulent cervical discharge is present 3

• Vaginal cultures are not first-line unless microscopy is inconclusive or treatment fails 4

Follow-Up Recommendations

• Patients should return only if symptoms persist or recur within 2 months 3, 2
• Routine test-of-cure is unnecessary if symptoms resolve 2
• For pregnant women, follow-up evaluation one month after treatment is recommended to verify cure 3