Diseases Characterized by Vaginal Discharge
Most women will have a vaginal infection, characterized by discharge, itching, or odor, during their lifetime. With the availability of complementary and alternative therapies and over-the-counter medications for candidiasis, many symptomatic women seek these products before or in addition to an evaluation by a medical provider.
Obtaining a medical history alone has been shown to be insufficient for accurate diagnosis of vaginitis and can lead to the inappropriate administration of medication. Therefore, a careful history, examination, and laboratory testing to determine the etiology of vaginal symptoms are warranted. Information on sexual behaviors and practices, gender of sex partners, menses, vaginal hygiene practices (e.g., douching), and self-treatment with medications should be elicited. The three diseases most frequently associated with vaginal discharge are BV (replacement of the vaginal flora by an overgrowth of anaerobic bacteria including Prevotella sp., Mobiluncus sp., G. vaginalis, Ureaplasma, Mycoplasma, and numerous fastidious or uncultivated anaerobes), T. vaginalis, and candidiasis. Cervicitis can also cause an abnormal discharge. Although vulvovaginal candidiasis (VVC) is usually not transmitted sexually, it is included in this section because it is frequently diagnosed in women who have vaginal symptoms or are being evaluated for STDs.
Various diagnostic methods are available to identify the etiology of an abnormal vaginal discharge. Clinical laboratory testing can identify the cause of vaginitis in most women and is discussed in detail in the sections of this report dedicated to each condition. In the clinician’s office, the cause of vaginal symptoms might be determined by pH, a potassium hydroxide (KOH) test, and microscopic examination of fresh samples of the discharge. The pH of the vaginal secretions can be determined by narrow-range pH paper; an elevated pH (i.e., >4.5) is common with BV or trichomoniasis. Because pH testing is not highly specific, discharge should be further examined microscopically by first diluting one sample in one or two drops of 0.9% normal saline solution on one slide and a second sample in 10% KOH solution (samples that emit an amine odor immediately upon application of KOH suggest BV or trichomoniasis). Coverslips are then placed on the slides, and they are examined under a microscope at low and high power.
The saline-solution specimen might show motile trichomonads or “clue cells” (i.e., epithelial cells with borders obscured by small bacteria), which are characteristic of BV. The KOH specimen typically is used to identify hyphae or blastospores seen with candidiasis. However, the absence of trichomonads in saline or fungal elements in KOH samples does not rule out these infections, because the sensitivity of microscopy is approximately 50% compared with NAAT (trichomoniasis) or culture (yeast) (475). The presence of WBCs without evidence of trichomonads or yeast may also suggest cervicitis (see Cervicitis).
In settings where pH paper, KOH, and microscopy are not available, alternative commercially available point-of-care tests or clinical laboratory testing can be used to diagnose vaginitis. The presence of objective signs of vulvar inflammation in the absence of vaginal pathogens after laboratory testing suggests the possibility of mechanical, chemical, allergic, or other noninfectious causes of vulvovaginal signs or symptoms. In patients with persistent symptoms and no clear etiology, referral to a specialist may be helpful.