Vaginal pH as a marker for bacterial pathogens and menopausal status

Our purpose was to confirm the elevation of vaginal pH expected in patients with bacterial pathogens in premenopausal women and to examine the relationship of serum follicle-stimulating hormone and estradiol levels to vaginal pH in menopausal patients without and with hormone replacement therapy.

Vaginal pH was determined by phenaphthazine (Nitrazine) pH paper in 253 patients seen in a solo private practice for routine speculum examination. None of the patients were pregnant. Measurements were made of serum levels of follicle-stimulating hormone and estradiol for 172 patients and vaginal cultures were taken from 82 patients. Vaginal pH was correlated with vaginal cultures and serum follicle-stimulating hormone and estradiol levels by use of statistical analysis.

Vaginal pH was elevated in all premenopausal patients with documented bacterial pathogens. Serum estradiol levels showed an inverse and serum follicle-stimulating hormone levels a direct statistical correlation with vaginal pH in menopausal patients.

Measurement of vaginal pH is useful, effective, and inexpensive for screening purposes. A vaginal pH of 4.5 is consistent with a premenopausal serum estradiol level and the absence of bacterial pathogens. An elevated vaginal pH in the 5.0 to 6.5 range suggests a diagnosis of either bacterial pathogens or decreased serum estradiol. In patients with an elevated pH, vaginal culture should establish the diagnosis. In the absence of bacterial pathogens, a vaginal pH of 6.0 to 7.5 is strongly suggestive of menopause. Titration of estradiol level by vaginal pH during estrogen replacement therapy may help menopausal women avoid side effects or cessation of therapy.