What are the initial steps for testing and treating vaginal itching?

Initial Testing and Treatment for Vaginal Itching

The initial diagnostic approach requires measuring vaginal pH and performing microscopic examination of vaginal discharge using both saline and 10% KOH preparations to differentiate between the three most common causes: bacterial vaginosis (40-50% of cases), vulvovaginal candidiasis (20-25%), and trichomoniasis (15-20%). 1, 2

Immediate Office-Based Testing

Step 1: Vaginal pH Measurement

• Use narrow-range pH paper on vaginal discharge; normal pH is ≤4.5 1
• pH >4.5 suggests bacterial vaginosis or trichomoniasis 1
• pH ≤4.5 with itching suggests vulvovaginal candidiasis 1, 3

Step 2: Microscopic Examination

Obtain vaginal discharge and prepare two slides immediately:

• Saline wet mount: Mix discharge with 1 mL normal saline to identify:

  • Motile trichomonads (flagellated organisms) 1
  • Clue cells (epithelial cells covered with bacteria) indicating bacterial vaginosis 1
  • Increased white blood cells suggesting infection 1
  • Yeast hyphae or budding yeast 1

• 10% KOH preparation: Add KOH to discharge to identify:

  • Yeast or pseudohyphae more clearly (KOH dissolves cellular material) 1
  • Perform "whiff test" - fishy amine odor indicates bacterial vaginosis 1

Critical timing: Read wet mount within 30 minutes to 2 hours for optimal detection of motile trichomonads 1

Diagnosis-Specific Treatment Algorithm

If pH ≤4.5 + Itching + Yeast on Microscopy = Vulvovaginal Candidiasis

First-line treatment options (choose one): 1

• Clotrimazole 1% cream 5g intravaginally daily for 7-14 days, OR
• Clotrimazole 2% cream 5g intravaginally daily for 3 days, OR
• Miconazole 2% cream 5g intravaginally daily for 7 days, OR
• Oral fluconazole 150 mg single dose 1, 4

Important caveat: Oral fluconazole is contraindicated in pregnancy and should not be used in children under 12 years 3, 4

If pH >4.5 + Clue Cells + Fishy Odor = Bacterial Vaginosis

Treatment: 1, 2

• Oral metronidazole, OR
• Intravaginal metronidazole, OR
• Intravaginal clindamycin

If pH >4.5 + Motile Trichomonads = Trichomoniasis

Treatment: 2

• Oral metronidazole or tinidazole
• Must treat sexual partners concurrently 2

When Microscopy is Negative or Equivocal

If symptoms persist despite negative microscopy, order confirmatory testing: 1

• Yeast culture for suspected candidiasis (wet mount misses 20-30% of cases) 1
• Nucleic acid amplification testing (NAAT) for trichomoniasis (wet mount sensitivity only 40-80%) 1, 2
• DNA probe testing for bacterial vaginosis if Gram stain unavailable 1
• Multiplex NAAT panels now available that test for all three conditions simultaneously 1

Common Pitfalls to Avoid

• Do not rely on symptoms alone - itching occurs in multiple conditions and cannot differentiate causes (LR range 0.18-0.79 for candidiasis) 5
• Do not delay microscopy - trichomonads require live organisms and motility for detection; sensitivity drops significantly after 2 hours 1
• Do not assume single pathogen - mixed infections can occur 2
• Do not treat empirically without testing in most cases, as clinical examination alone has poor diagnostic accuracy 5

Special Population Considerations

Pediatric Patients

• Mandatory STI evaluation required for any child with vaginal symptoms, including cultures for N. gonorrhoeae and C. trachomatis 6
• Any STI diagnosis requires reporting to child protective services 6
• Implement hygiene measures first: gentle cleansing with water only, cotton underwear, front-to-back wiping 3, 6

Pregnant Patients

• Use only topical azoles - avoid oral fluconazole due to risk of spontaneous abortion and congenital defects 1, 4
• Test and treat bacterial vaginosis to reduce postpartum endometritis 1