Is the vulva considered part of the female genitals and does its microflora resemble that of the vagina?

The Vulva as Part of Female Genitals and Its Microbiome

The vulva is definitively considered part of the female genitals, and while its microbiome shows similarities to the vaginal microbiome, it has distinct characteristics with higher diversity and includes commensals of both cutaneous and fecal origin. 1

Anatomical Classification and Microbiome Composition

Vulva as Part of Female Genitals

• The vulva is an integral component of the female genital system, comprising the external genital structures including the labia majora, labia minora, clitoris, and vestibule
• It serves as the external entrance to the vagina and is functionally and anatomically connected to the internal reproductive organs

Vulvar Microbiome Characteristics

• The vulvar microbiome shares some similarities with the vaginal microbiome but is not identical 1
• Common bacterial genera found on the vulva include:
  • Lactobacillus (also predominant in vagina)
  • Corynebacterium
  • Staphylococcus
  • Prevotella 1

Key Differences from Vaginal Microbiome

• The vulvar microbiome generally displays higher diversity compared to the vaginal microbiome 1
• It contains microorganisms of:
  • Cutaneous origin (skin bacteria)
  • Fecal origin (due to anatomical proximity)
  • Vaginal origin (due to discharge and anatomical continuity) 1

Clinical Implications

Diagnostic Considerations

• When assessing genital infections, it's important to recognize that vulvar and vaginal infections may present differently due to their distinct microbiomes
• The pH of the vulva tends to be higher than the vaginal pH, which is typically maintained at ≤4.5 in healthy women 2

Treatment Approaches

• For conditions affecting both vulva and vagina:
  • Daily lukewarm baths (30 minutes) can help remove discharge and debris 2
  • Mild antiseptic baths with chlorhexidine, octenidine, or polyhexanide may be considered for recurrent infections 2

Common Pitfalls in Clinical Practice

• Misattributing vulvar symptoms to vaginal infections without proper assessment
• Failing to recognize that treatments effective for vaginal infections may not adequately address vulvar conditions due to microbiome differences
• Not accounting for the influence of external factors (clothing, hygiene products, etc.) on the vulvar microbiome that wouldn't affect the vaginal environment

Scientific Understanding of Vaginal vs. Vulvar Microbiome

The vaginal microbiome is characterized by:

• Dominance of Lactobacillus species, particularly in healthy women 3, 4
• Low microbial diversity in healthy states 5
• Production of lactic acid that maintains acidic pH 5
• Dynamic changes influenced by hormonal fluctuations 4

In contrast, the vulvar microbiome:

• Shows similarities to the vaginal microbiome but with greater diversity 1
• Contains microorganisms from both the skin and vaginal environments 1
• Is more exposed to external influences and contaminants
• Has not been studied as extensively as the vaginal microbiome 1

The most recent and comprehensive systematic review on this topic (2021) confirms that while there are similarities between vulvar and vaginal microbiomes, the vulvar microbiome represents a distinct ecological niche with its own characteristics and deserves separate consideration in both research and clinical practice 1.