Interesting things to know about Vaginal pH

Many years ago a urology doctor shared the skill of testing vaginal pH as part of my pelvic floor exam.  I’ve since used it to gather objective data around estrogen status, often finding elevated levels in post-partum, breastfeeding, and peri and post-menopausal women. When correlated with symptoms and visual skin changes this can be a helpful tool to both direct treatment and monitor treatment effectiveness. 

To perform pH testing, place a pH strip into the distal vagina. Let it sit there for a few seconds to absorb vaginal moisture. Remove and record results. Any concerning changes in vaginal pH can be documented and reported back to your patient’s medical provider.

Here’s a quick tour through the research on vaginal pH. I hope you enjoy learning and consider adding vaginal pH testing to your clinical practice.

-Normal vaginal pH is considered to range between 4.0 and 5.0 in menstruating women (Garcia-Closas)

-Intervaginal pH does not vary between vaginal location (proximal, mid, distal)

-Clinician test vs self-test results vary slightly but not significantly (Ferris)

-Low serum estradiol levels are associated with high vaginal pH values

-Vaginal pH of 4.5 is indicative of premenopausal estradiol levels and the absence of bacterial overgrowth

-Vaginal pH of 5.0 to 6.5 may indicate either estrogen changes or bacterial overgrowth, a culture may be warranted

-Vaginal pH of 6.0 to 7.5 is strongly suggestive of menopause

-Vaginal pH measurements can be helpful in determining the efficacy of treatment with vaginal estrogen (Caillouette)

-Vaginal pH levels (high) were as sensitive as blood serum FSH levels in the detection of menopause status (Roy) and (Panda)

-Understanding of the vaginal microbiome and its effect on vaginal pH continues to evolve

-“Although lactic acid (produced by Lactobacillus) is the primary acid in normal vaginal secretions, other organic acids such as acetic, mydriatic, and linoleic acid are also normally found in vaginal fluid.  Some healthy women actually lack vaginal Lactobacilli, but their vaginal pH is in the normal (moderately acidic) range, and other lactic acid-producing bacteria, such as Atopobium, Megasphaera, and/or Leptotrichia species, are present.”

-Lactic acid is also a byproduct of anaerobic glucose metabolism within the cells of the vaginal mucosa

-The summation of vaginal pH is determined by both the vaginal mucosal metabolism (which is influenced by estrogen) and the vaginal microbiome, both of which are unique to each female

-Vaginal pH is around 5 in newborns, before colonization from microbes, rises to neutral range by 6 weeks of life, and falls when puberty ushers in an increase in estrogen

-Normal vaginal pH helps to keep optimal inflammatory responses and skin barrier functions in vaginal and vulvar skin.  Elevated pH in menopause leads to susceptibility to vulvar contact dermatitis

-Topical application to the menopausal vagina restores surface pH and lowers infection risk

-Candida infections do not alter vaginal pH

-STI via chlamydia, gonorrhea, or trichomonas as well as bacterial vaginosis may cause elevations in vaginal pH (Linhares)

- “Detection of HPV was positively associated with vaginal pH, mainly in women < 35 years. Elevated vaginal pH was associated with 30% greater risk of infection with multiple HPV types and with LSIL (low-grade intraepithelial lesions), predominantly in women younger than 35 and 65+ years of age. Detection of C. trachomatis DNA was associated with increased vaginal pH in women < 25 years” (Clarke)

-pH self-testing during pregnancy and treatment of underlying infections positively impacted preterm birth rates (Holyoke and Saling)

-The microbiome in humans is generally >70% Lactobacilli, where other mammals have 1% or less

-Average pH of 21 non-human mammals is 5.4 to 7.8

-Authors propose that the high level of starch in human diets contributes to increased levels of vaginal glycogen which in turn proliferates lactobacilli…continued research will contribute to our collective knowledge base (Miller)

-Vaginal microbiome variability may have an effect on fertility (Xu)

-Douching with an over-the-counter lactic acid containing douche: did not significantly affect vaginal pH or microbiome composition and may promote candida infections (van der Veer)

Linhares. Vaginal pH and Lactobacilli. Am J Obstet Gynecol 2011.

References:

Caillouette, J. C., Sharp Jr, C. F., Zimmerman, G. J., & Roy, S. (1997). Vaginal pH as a marker for bacterial pathogens and menopausal status. American journal of obstetrics and gynecology, 176(6), 1270-1277.

Clarke, M. A., Rodriguez, A. C., Gage, J. C., Herrero, R., Hildesheim, A., Wacholder, S., ... & Schiffman, M. (2012). A large, population-based study of age-related associations between vaginal pH and human papillomavirus infection. BMC infectious diseases, 12(1), 1-9.

Ferris, D. G., Francis, S. L., Dickman, E. D., Miler-Miles, K., Waller, J. L., & McClendon, N. (2006). Variability of vaginal pH determination by patients and clinicians. The Journal of the American Board of Family Medicine, 19(4), 368-373.

García-Closas, M., Herrero, R., Bratti, C., Hildesheim, A., Sherman, M. E., Morera, L. A., & Schiffman, M. (1999). Epidemiologic determinants of vaginal pH. American journal of obstetrics and gynecology, 180(5), 1060-1066.

Hoyme, U. B., & Saling, E. (2004). Efficient prematurity prevention is possible by pH-self measurement and immediate therapy of threatening ascending infection.

Linhares, I. M., Summers, P. R., Larsen, B., Giraldo, P. C., & Witkin, S. S. (2011). Contemporary perspectives on vaginal pH and lactobacilli. American journal of obstetrics and gynecology, 204(2), 120-e1.

Miller, E. A., Beasley, D. E., Dunn, R. R., & Archie, E. A. (2016). Lactobacilli dominance and vaginal pH: Why is the human vaginal microbiome unique?. Frontiers in microbiology, 7, 1936.

Panda, S., Das, A., Santa Singh, A., & Pala, S. (2014). Vaginal pH: A marker for menopause. Journal of mid-life health, 5(1), 34.

Roy, S., Caillouette, J. C., Roy, T., & Faden, J. S. (2004). Vaginal pH is similar to follicle-stimulating hormone for menopause diagnosis. American journal of obstetrics and gynecology, 190(5), 1272-1277.

Xu, J., Bian, G., Zheng, M., Lu, G., Chan, W. Y., Li, W., ... & Du, Y. (2020). Fertility factors affect the vaginal microbiome in women of reproductive age. American Journal of Reproductive Immunology, 83(4), e13220.

Van Der Veer, C., Bruisten, S. M., Van Houdt, R., Matser, A. A., Tachedjian, G., van de Wijgert, J. H. H. M., ... & van der Helm, J. J. (2019). Effects of an over-the-counter lactic-acid containing intra-vaginal douching product on the vaginal microbiota. BMC microbiology, 19(1), 1-13.

*Citations are noted at the end of each article summary

This product was recommended by S. Roy for accurate testing: