What is the guideline for diagnosing and treating vaginitis in a patient presenting with symptoms such as itching, burning, abnormal discharge, or odor?

Vaginitis Diagnosis and Treatment Guidelines

Diagnostic Approach

Diagnose vaginitis through vaginal pH measurement and microscopic examination of fresh vaginal discharge using both saline and 10% KOH preparations, combined with the whiff test to differentiate between the three most common causes: bacterial vaginosis, vulvovaginal candidiasis, and trichomoniasis. 1, 2

Initial Diagnostic Steps

• Measure vaginal pH using narrow-range pH paper: pH >4.5 indicates bacterial vaginosis or trichomoniasis, while pH 4.0-4.5 suggests candidiasis 3, 4
• Perform wet mount microscopy by diluting vaginal discharge in 1-2 drops of 0.9% normal saline on one slide and 10% KOH on a second slide 3
• Conduct the whiff test by applying 10% KOH to the discharge; a fishy amine odor immediately after application indicates bacterial vaginosis or trichomoniasis 3
• Examine both preparations microscopically at low- and high-dry power to identify specific pathogens 3

Microscopic Findings by Condition

• Bacterial vaginosis: Clue cells (epithelial cells with adherent bacteria obscuring borders) visible on saline preparation 3, 4
• Trichomoniasis: Motile Trichomonas vaginalis organisms in saline preparation 3
• Candidiasis: Yeast or pseudohyphae more easily identified in KOH preparation 3

Additional Testing Considerations

• Obtain nucleic acid amplification testing (NAAT) for Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis from vaginal swab, as wet mount microscopy has low sensitivity for trichomoniasis 1
• Culture for Trichomonas vaginalis is more sensitive than microscopic examination when initial microscopy is negative 3
• Avoid culturing Gardnerella vaginalis as it lacks specificity and can be isolated from 50% of normal women 3

Bacterial Vaginosis

Diagnostic Criteria (Amsel Criteria)

Diagnose bacterial vaginosis when three of the following four criteria are present: 3

• Homogeneous, white, noninflammatory discharge that smoothly coats the vaginal walls 3, 4
• Presence of clue cells on microscopic examination 3
• Vaginal pH >4.5 3
• Positive whiff test (fishy odor before or after adding 10% KOH) 3

Treatment Regimens

First-line treatment: Metronidazole 500 mg orally twice daily for 7 days 3, 1, 2

• Critical warning: Patients must avoid alcohol during treatment and for 24 hours after completion 3

Alternative regimens: 3, 2

• Metronidazole 2 g orally as a single dose 3
• Metronidazole gel 0.75% intravaginally once daily for 5 days 2
• Clindamycin 2% cream intravaginally at bedtime for 7 days 3, 2

Special Considerations

• Treat only symptomatic women, as approximately 50% of women meeting diagnostic criteria are asymptomatic 3
• Do not treat male sexual partners, as this has not been shown to prevent recurrence 3
• Consider treatment before surgical abortion procedures (even if asymptomatic), as bacterial vaginosis is associated with post-abortion pelvic inflammatory disease 3
• Expect high recurrence rates of 50-80% within one year, which may require repeated treatment courses 2

Vulvovaginal Candidiasis

Diagnostic Features

• Clinical presentation: Vulvar pruritus, erythema, and thick white "cottage cheese-like" discharge 2, 4
• Vaginal pH: Normal (4.0-4.5) 4, 5
• Microscopy: Yeast or pseudohyphae visible on KOH preparation 3, 2

Treatment Regimens

First-line treatment for uncomplicated cases: Topical intravaginal azoles with 80-90% efficacy 2

Recommended topical options: 2

• Clotrimazole 1% cream 5g intravaginally for 7-14 days 2
• Clotrimazole 500mg vaginal tablet as a single dose 2
• Miconazole 2% cream 5g intravaginally for 7 days 2
• Terconazole 0.8% cream 5g intravaginally for 3 days 2

Alternative oral treatment: Fluconazole (oral) for non-pregnant patients 1, 6

Critical Warnings

• Use only topical azoles during pregnancy; oral fluconazole is contraindicated 1, 6
• Do not treat based solely on clinical appearance, as 10-20% of women normally harbor Candida without symptoms 2

Trichomoniasis

Diagnostic Features

• Clinical presentation: Frothy, yellow-green discharge with vulvar itching and irritation 4
• Vaginal pH: >4.5 (often >5.4) 4, 5
• Microscopy: Motile trichomonads visible on saline wet mount 3, 4
• Whiff test: Positive (fishy odor) 4, 5

Treatment Regimens

Recommended treatment: Metronidazole 2g orally as a single dose 1

Critical requirement: Treat sexual partners simultaneously with metronidazole 2g single dose to prevent reinfection 1, 6

Pregnancy considerations: Metronidazole 2g single dose is safe and recommended during pregnancy 1

Differential Diagnosis Pitfalls

When Vulvar Inflammation Exists Without Pathogens

• Consider mechanical, chemical, allergic, or noninfectious irritation when objective signs of vulvar inflammation are present with minimal discharge and no identifiable pathogens on microscopy 3, 4

When Cervicitis May Be the Cause

• Test for Chlamydia trachomatis and Neisseria gonorrhoeae via NAAT, as mucopurulent cervicitis can sometimes present with vaginal discharge 3, 1

When Laboratory Testing Fails

• Laboratory testing fails to identify a cause in a substantial minority of women with vaginitis symptoms 3
• In these cases, consider atrophic vaginitis, irritant/allergic vaginitis, or inflammatory vaginitis 6