What happens to the vaginal pH in Trichomonas (Trichomonas vaginalis) vaginitis?

From the Guidelines

In Trichomonas vaginalis vaginitis, the vaginal pH typically increases above the normal range of 3.8-4.5, often rising to greater than 4.5, as indicated by studies such as 1. This elevation in pH occurs because T. vaginalis organisms disrupt the normal vaginal flora, particularly reducing the population of protective Lactobacillus species. Some key points to consider include:

• Lactobacilli normally maintain vaginal acidity by producing lactic acid and hydrogen peroxide, creating an environment inhospitable to pathogens.
• When T. vaginalis infects the vagina, it not only directly damages epithelial cells but also creates conditions that favor its own growth by raising the pH.
• The parasite itself thrives in a less acidic environment.
• This pH elevation is clinically significant and is one of the diagnostic criteria used when evaluating vaginal infections, as noted in guidelines such as 1 and 1.
• The increased pH can be detected using pH paper during examination and helps differentiate trichomoniasis from other vaginal conditions like bacterial vaginosis (which also shows elevated pH) and vulvovaginal candidiasis (which typically maintains normal pH), as discussed in 1. Understanding this pH change is important for proper diagnosis and subsequent treatment with appropriate antiprotozoal medications, with the most recent and highest quality study 1 providing guidance on diagnostic approaches.

From the Research

Vaginal pH in Trichomonas Vaginitis

• The vaginal pH in Trichomonas vaginitis is higher than in healthy women, with a median pH of 6 in patients with symptomatic Trichomonas vaginitis, compared to a median pH of less than or equal to 4.5 in healthy women 2.
• A study found that Trichomonas vaginalis infection was associated with a higher vaginal pH, particularly in women with intermediate Nugent scores, indicating a possible link between vaginal pH and the presence of Trichomonas vaginalis 3.
• The relationship between vaginal pH and Trichomonas vaginalis infection is complex, and more research is needed to fully understand the mechanisms involved.
• Vaginal pH is an important factor in the diagnosis and treatment of vaginitis, including Trichomonas vaginitis, and self-test products are available to measure vaginal pH 4.

Comparison of Vaginal pH in Different Studies

• A study published in 1992 found that the median vaginal pH in patients with Trichomonas vaginitis was 6, while a study published in 2018 found that vaginal pH was higher in women with Trichomonas vaginalis infection and intermediate Nugent scores 2, 3.
• The differences in vaginal pH between studies may be due to various factors, including the population studied, the methods used to measure vaginal pH, and the presence of other vaginal infections.

Clinical Implications

• The higher vaginal pH in Trichomonas vaginitis may have implications for the diagnosis and treatment of the infection, particularly in terms of the use of metronidazole therapy 2, 5.
• Further research is needed to fully understand the relationship between vaginal pH and Trichomonas vaginalis infection, and to develop effective diagnostic and treatment strategies for this common vaginal infection.