Classification of Vulvovaginitis
Vulvovaginitis is classified into three major infectious categories—bacterial vaginosis, vulvovaginal candidiasis, and trichomoniasis—plus non-infectious causes, with classification based on etiology, clinical presentation, and in the case of candidiasis, complexity of disease. 1
Primary Etiologic Classification
The three most common infectious causes account for approximately 90% of vulvovaginitis cases 1, 2:
1. Bacterial Vaginosis (BV)
- Caused by replacement of normal H₂O₂-producing Lactobacillus species with overgrowth of anaerobic bacteria (Prevotella, Mobiluncus), Gardnerella vaginalis, and Mycoplasma hominis
- Most prevalent cause of vaginal discharge or malodor
- Vaginal pH >4.5
- Not exclusively sexually transmitted, though associated with sexual activity 1
2. Vulvovaginal Candidiasis (VVC)
- Usually caused by Candida albicans, occasionally other Candida species or yeasts
- Vaginal pH <4.5 (normal)
- Affects 75% of women at least once; 40-45% have two or more episodes 1
- Further subclassified as:
3. Trichomoniasis
- Caused by Trichomonas vaginalis
- Vaginal pH >4.5
- Sexually transmitted infection requiring partner treatment 1
4. Other Infectious Causes
- Mucopurulent cervicitis from Chlamydia trachomatis or Neisseria gonorrhoeae can present with vaginal discharge 1
- Less common bacterial pathogens (Haemophilus influenzae, beta-hemolytic streptococci, Streptococcus pneumoniae, Staphylococcus aureus) occur in 5.6% of cases, particularly in prepubertal children and postmenopausal women 4
5. Non-Infectious Causes
- Mechanical, chemical, or allergic irritation
- Foreign body
- Desquamative inflammatory vaginitis
- Genitourinary syndrome of menopause
- Contact dermatitis 1, 5, 6, 7
Diagnostic Classification Approach
The classification is determined algorithmically using 1, 2:
Step 1: Measure vaginal pH
- pH <4.5 → Consider VVC or non-infectious causes
- pH >4.5 → Consider BV or trichomoniasis
Step 2: Perform microscopy
- Saline wet mount: Identifies motile trichomonads (trichomoniasis) or clue cells (BV)
- 10% KOH preparation: Identifies yeast/pseudohyphae (VVC); positive "whiff test" (amine odor) suggests BV
Step 3: Clinical criteria
- BV diagnosis requires 3 of 4 Amsel criteria: homogeneous white discharge, clue cells, pH >4.5, positive whiff test 1
- VVC diagnosis: Pruritus, erythema, white discharge with yeasts/pseudohyphae on microscopy or positive culture in symptomatic patient 1
Important Clinical Distinctions
Age-Based Patterns
Prepubertal children and postmenopausal women have higher rates of non-candidal bacterial pathogens, warranting bacterial culture when empiric treatment fails 4.
Complexity Classification for VVC
This distinction is critical because complicated VVC requires longer treatment duration and different management strategies than uncomplicated disease. Recurrent VVC (≥3 episodes/year) affects approximately 9% of women and requires maintenance therapy 3.
Key Diagnostic Pitfalls
- Microscopy sensitivity is only 40-70% for both trichomoniasis and VVC compared to NAAT and culture 2
- Asymptomatic colonization with Candida (10-20% of women) or G. vaginalis (50% of women) should not be treated 1
- Mixed infections can occur; VVC can coexist with STDs 1
- Laboratory testing fails to identify a cause in 25-40% of cases despite symptoms 2, 8
- Gram stain for BV (Nugent scoring) is more specific than culture or probe testing for G. vaginalis alone 2, 4
When empiric treatment fails, bacterial culture should be performed to detect all potentially pathogenic organisms, particularly in children and postmenopausal women where atypical pathogens are more common 4.