Vaginal Discharge.

Essentials of Diagnosis of vaginal discharge.

 Patient complaints and sexual history.

 Appearance of the discharge (character and color).

 Vaginal pH higher than 4.5.

 Presence of motile trichomonads, yeast or pseudohyphae, or clue cells on light microscopy.

 Positive "whiff" test.

 

General Considerations

Vaginal discharge is a common complaint that is often considered trivial and thus incorrectly managed by the clinician. Empiric diagnosis and treatment based on either history or appearance of the discharge alone is inadequate and frequently results in inappropriate treatment and repeated visits by the patient. When considering the etiology of vaginitis it is important to take into account the patient's age and sexual history. Lactobacilli, the predominant bacteria in the vagina of a healthy premenopausal woman, are typically absent in women who are menopausal and not receiving estrogen replacement therapy. The estrogen-deficient vaginal epithelium in postmenopausal women is also thinner; thus, atrophic vaginitis is a consideration in this age group. For sexually active women, sexually transmitted diseases (STDs) such as trichomoniasis, genital herpes, gonorrhea, and chlamydia should be considered.

Pathogenesis

The three major causes of vaginal discharge during the reproductive years are candidiasis, bacterial vaginosis, and trichomoniasis. The latter is the only one of the three that is known to be sexually transmitted; however, bacterial vaginosis is clearly associated with sexual activity. In addition, vaginal candidiasis is frequently seen in the setting of increased sexual activity, likely due to colonizing organisms that gain entry to the epithelium via microabrasions from sexual intercourse. In older women, as previously mentioned, atrophic vaginitis should be considered.

Other STDs, such as gonorrhea, chlamydia, and genital herpes, may lead to vaginal complaints. However, the physical signs of gonorrhea and chlamydia are cervical inflammation, not vaginal discharge. Genital herpes may cause discharge along with ulceration.

Some other causes of vaginal discharge include retained foreign body, cytolytic vaginosis, and desquamative inflammatory vaginitis. It should be noted that some women perceive their vaginal discharge to be abnormal when it is simply physiologic.

Prevention

Use of condoms is protective against STDs and also appears to protect against acquisition of bacterial vaginosis. If an STD is diagnosed, the patient's sex partners should be treated to avoid reinfection. Episodes of recurrent bacterial vaginosis may be prevented by use of twice weekly intravaginal metronidazole gel. Similarly, recurrent vaginal candidiasis can be controlled with use of once weekly fluconazole (150 mg). Estrogen replacement therapy will prevent atrophic vaginitis.

Clinical Findings

Symptoms and Signs

Patients should be asked about the consistency and color of the discharge and whether it is accompanied by pruritus (internal and external), irritation, or a fishy odor. Another useful question is whether a fishy odor is present after unprotected intercourse (a characteristic finding in bacterial vaginosis). During the examination, the clinician should note the presence or absence of vaginal ulcerations, erythema, characteristics (color and consistency) of the discharge, and the appearance of the cervix (mucopus at the os may suggest gonorrhea or chlamydia).

Laboratory Findings

The most widely used tests for the diagnosis of vaginitis are vaginal pH evaluation, the so-called "whiff" test, and light microscopy (see Table 2–1). Light microscopy is the most helpful of the three tests.

Vaginal pH

The vaginal pH is best measured using pH paper strips (ColorpHast indicator strips, EM Science, Gibbstown, NJ). The color resulting from contact of the vaginal fluid with the indicator paper can be compared directly with the color chart on the container. When collecting specimens for pH evaluation, care should be taken to avoid cervical secretions. These are normally more alkaline than secretions from the healthy vagina and may falsely influence the pH reading. Other factors that can influence the pH result are semen and blood in the sample. Semen is alkaline, and blood obscures the color change on the indicator paper.

The vaginal pH is normally 4.5 in the presence of predominantly lactobacillus flora; this includes the healthy vagina as well as one in which yeast infection is present. An elevated pH is indicative of bacterial vaginosis or trichomoniasis, although in some patients with trichomoniasis, the pH may be normal.

"Whiff" Test

The most expeditious way to collect the vaginal specimen for both the "whiff" test and microscopy is to place a generous amount of vaginal discharge collected from the lateral vaginal wall into a small glass tube containing 0.3 mL of normal saline. This method allows for preparation of cover-slipped slides at the microscope, and for multiple preparations if required. The "whiff" test is performed by mixing a drop of the vaginal saline mixture with 10% potassium hydroxide (KOH) and then sniffing for a fishy smell. The fishy odor indicates the presence of volatilized amines associated with the anaerobic flora typical of bacterial vaginosis; however, the test is highly subjective.

Light Microscopy

The cover-slipped specimen is examined at 400 x magnification under reduced light. When examining the fluid, the clinician should note the presence of white blood cells, parabasal cells, motile trichomonads, budding yeast and pseudohyphae, clue cells, and bacteria (specifying the type, if present). White blood cells are frequently present in vaginal secretions of patients with candidiasis and trichomoniasis. They may also be present, along with parabasal cells, in women with atrophic vaginitis or desquamative inflammatory vaginitis. White blood cells may also be seen in patients with bacterial vaginosis as a result of a vaginal or cervical coinfection. Although direct microscopic examination of the vaginal fluid for motile trichomonads is the fastest, least expensive diagnostic method for trichomoniasis, the sensitivity of this test compared with culture is only 60%.

Perhaps the most difficult diagnosis to confirm microscopically is that of candidiasis. The presence of budding yeast without the report of symptoms compatible with a yeast infection may simply represent colonization. On the other hand, clumps of pseudohyphae in vaginal secretions of a patient with candidiasis can be difficult to visualize and may require examination of multiple preparations. The addition of KOH, which dissolves other cellular elements, may be helpful.

Amsel Criteria

The most commonly used diagnostic method for bacterial vaginosis is the Amsel criteria, which comprises four findings: (1) a homogenous vaginal discharge, (2) vaginal pH higher than 4.5, (3) positive "whiff" test, and (4) clue cells on direct microscopic examination of the vaginal fluid (wet mount). If three of these four findings are present, the diagnostic criteria for bacterial vaginosis are met. Clue cells, defined as squamous epithelial cells covered with bacteria to the extent that the edges of the cell are obscured, are also subject to the interpretation of the microscopist. The careful observer, however, will go beyond the Amsel criteria to note the amount and morphotypes of the vaginal bacteria in the wet mount. In bacterial vaginosis, there will be many coccobacillary morphotypes and a paucity of large rods, which represent the lactobacilli. Motile curved rods, which represent Mobiluncus, are pathognomonic for bacterial vaginosis.

Special Tests

Additional tests are commercially available for point-of-care testing of vaginitis. Several rapid card tests are available. One test detects proline aminopeptidase, an enzyme found in the vaginal secretions of women with bacterial vaginosis (QuickVue Advance G vaginalis Test, Quidel Corporation, San Diego, CA). A second test detects elevated pH and amines (QuickVue Advance pH and Amines Test Card, Quidel Corporation, San Diego, CA) and may be a useful screening tool for determining patients who should receive a more thorough evaluation. A third, rapid colorometric test for the diagnosis of bacterial vaginosis detects sialidase in the vaginal fluid (Osom BVBlue Test, Genzyme Corporation, Cambridge, MA). A semiautomated test for vaginitis, which includes trichomoniasis, candidiasis, and bacterial vaginosis, is also available (Affirm VPIII, Becton Dickinson, Sparks, MD). A point-of-care enzyme-linked immunosorbent assay (ELISA)–based test for trichomonas has recently been licensed (Osom Trichomonas Rapid Test, Genzyme Corporation, Cambridge, MA). This strip test is used with vaginal secretions, has a sensitivity of approximately 80% compared with culture, and is easy to perform.

Routine bacterial culture of vaginal secretions is not helpful and can be misleading. Culturing for Trichomonas vaginalis may be helpful in patients without a confirmed diagnosis, because culture is more sensitive for the diagnosis of trichomoniasis than the wet mount.

Differential Diagnosis

Other causes of vaginal discharge include atrophic vaginitis, retained foreign body, cytolytic vaginitis, desquamative inflammatory vaginitis, genital herpes, physiologic discharge, and perhaps gonorrhea or chlamydia. Vaginal complaints should never be diagnosed without analyzing objective laboratory data except, perhaps, in the case of recurrent infections that have been previously documented.

Complications

Bacterial vaginosis is associated with obstetric and gynecologic complications. In cross-sectional studies, bacterial vaginosis is a risk factor for preterm birth and low birth weight. However, prospective treatment studies have yielded inconsistent results as to the benefit of screening and treating for bacterial vaginosis in pregnancy. Gynecologic complications include postoperative infections following gynecologic surgery; acquisition of sexually transmitted diseases, including pelvic inflammatory disease; acquisition and transmission of HIV; and recurrent urinary tract infections. Screening and treating for bacterial vaginosis prior to elective gynecologic procedures is recommended.

Trichomoniasis has also been associated with preterm birth and acquisition and transmission of HIV.

Treatment

Table 2–2 summarizes drug treatment for vaginal infections. Treatment should be targeted specifically at the cause of the vaginal discharge; empiric therapy should always be avoided. In the case of trichomoniasis, sex partners should also be treated.

When to Refer to a Specialist

Women with recurrent or persistent infections may be referred to an infectious disease specialist or gynecologist for additional management. If the cause of the vaginal discharge cannot be identified, consultation with those specialists may also be helpful.

Prognosis

The overall prognosis is excellent; however, bacterial vaginosis cure rates are 70–80%, and recurrence rates may be as high as 50% within 6 months.

Practice Points

 When collecting specimens for pH evaluation, care should be taken to avoid cervical secretions. These are normally more alkaline than secretions from the healthy vagina and may falsely influence the pH reading.