Vaginal Infections

What are the common causes of vaginal discharge? Can a diagnosis of vaginitis be made solely by clinical history? On what basis should a diagnosis of vaginal infections be made? What is the best way to evaluate patients for vaginal discharge? How should vaginal infections be treated? What if a patient has recurrent symptoms? How should a pregnant patient be treated?

Vaginitis accounts for more than 10 million office visits per year. In 1995 alone, $170 million was spent on over-the-counter vaginitis medications. Are these dollars being expended wisely? This article outlines an approach that primary-care physicians can adopt in evaluating, diagnosing, and treating this common malady. Clinical history and symptoms alone are inadequate to make a diagnosis.
What are the common causes of vaginal discharge?

All women have a certain amount of normal vaginal discharge. The healthy vagina produces fluid that changes in quality and quantity throughout the menstrual cycle. At the time of ovulation, many women notice a clear, thin discharge that is conducive to sperm motility. Prior to menstruation, the discharge may be homogeneous, white, and thick.

The differential diagnosis (Table 1) for vaginal symptoms includes cervical infection, such as gonorrhea or chlamydia; hypersensitivity reactions from medications, soaps, or clothing; and urinary incontinence/infection or vulvovestibulitis. However, the most common cause of vaginal symptoms is infection: bacterial vaginosis (BV) (40-50percent), candidal vaginitis (20-25percent), and trichomonal vaginitis (IS-20 percent).

Bacterial vaginosis is an overgrowth of normal vaginal bacteria; the number of organisms may reach 1000 times the normal level; anaerobic bacteria predominate. Gardnerella vaginalis, once thought to be a causative organism, is found in 50 percent of normal women; now it is clear that BV is not caused by a single organism. Its overgrowth may wax and wane; recurrence after treatment is common, as is spontaneous resolution in untreated women.

Bacterial vaginosis is asymptomatic in up to 50 percent of women. Symptomatic women note increased discharge, itching, or a fishy odor, particularly after intercourse. Unlike other vaginal infections, there is no associated inflammation; hence, the term "vaginosis" rather than "vaginitis."

Candida albicans is the most common cause of yeast vaginitis. However, this fungus is a constituent of normal flora in roughly 25 percent of asymptomatic women of childbearing age. Up to 75 percent of women will have one candidal vaginal infection, and 40 percent will have two or more. The most common symptom of candidal vaginitis is vaginal itching.

Vaginitis due to Trichomonas spp. is the most common, nonviral, sexually transmitted disease in the world. This protozoa causes acute urethritis in men and women, as well as inflammation in the glands surrounding the vaginal introitus. The presence of Trichomonas spp. can alter the normal balance in the vagina, making BV a common accompanying condition. Trichomonal vaginitis is asymptomatic in up to 50 percent of female and 90 percent of male carriers.
Can a diagnosis of vaginitis be made solely by clinical history?

Physicians and patients often attempt to diagnose vaginal infections from clinical history alone, using specific symptoms, such as itching, odor, increased or colored discharge, and pain with intercourse, to guide therapy. Numerous studies have identified two main problems with this approach.

First, no prospective trial has found patient symptoms reliable enough to guide diagnosis and treatment. Verification of infection must be made with microscopic examination or culture of the vaginal discharge. Itching alone is insufficient to diagnose candidal infection without microscopic proof of yeast forms. This is an important point to make to patients who use over-the-counter medications to self-treat without a definite diagnosis. The only exception is the woman with vaginal pruritus and discharge who has just completed a course of antibiotics. Her symptoms and history alone are adequate for one empiric course of topical antifungal therapy.

Second, among women who have symptoms suggesting a vaginal infection, a known pathogen is identified in only 50 percent of the patients through gold-standard laboratory techniques. In the remainder, there is no clear infectious cause, and no antimicrobial treatment is indicated.

Unnecessary expense, continued symptoms from missed diagnoses, and medication side effects are all potential problems caused by therapy based on history alone.
On what basis should a diagnosis of vaginal infections be made?

Although it is tempting to evaluate a patient on history alone, vaginal fluid analysis is quick and critical to diagnostic accuracy. Easily performed in-office tests include pH, microscopy, and the whiff test Table 2). Gram's stain is not needed, and a Pap smear is inadequate for any diagnosis.

The most widely accepted approach to diagnosing BV makes use of Amsel's criteria and requires three of the following four findings: pH >4.5; positive whiff test; thin, homogeneous discharge; and clue cells on the microscopic exam. Culture of the discharge is not helpful, as BV is an overgrowth of normal flora. Since BV is not associated with inflammation, excessive numbers of white blood cells (WBCs) are not seen on a wet mount. Their presence indicates additional infections.

A diagnosis of candidal vaginitis is made by identifying hyphae and budding spores on microscopic evaluation of the KOH slide. Significant candidal vaginitis is associated with many WBCs, indicative of accompanying inflammation. Culture, although rarely indicated, is appropriate if microscopic evaluation is negative and clinical suspicion remains high. Culture may also be appropriate in recurrent or relapsing infection when more specific identification of the yeast species would help guide treatment. A positive culture, however, does not definitively implicate yeast as the cause of symptoms, given the high rate of colonization with this organism in asymptomatic healthy populations.

Trichomonal vaginitis is most commonly diagnosed by visualizing motile trichomonads on microscopic examination of vaginal discharge. Microscopic identification of trichomonads is highly operator-dependent, and the rate of false negatives may be as high as 50 percent. Therefore, if clinical suspicion is high and microscopic examination is negative, send the vaginal sample for culture. Positive results, with a sensitivity approaching 90 percent, commonly are available within two days.
What is the best way to evaluate patients for vaginal discharge?

A sample of vaginal fluid gathered during a speculum examination is essential for evaluating vaginal symptoms or abnormal discharge.

First, view the external genitalia to rule out perivaginal etiology of symptoms. With the speculum in place, examine the cervix. Purulent discharge from the cervical os requires culture for gonorrhea and chlamydia. (Cervicitis may he caused by other vaginal flora, such as Ureaplasma spp., but this is uncommon.) Then proceed in the following manner:

Place the pH paper against the vaginal wall or in the discharge remaining on the speculum after the exam. Normal pH ranges from 4.0-4.5. A pH >4.5 suggests BV, estrogen deficiency, or occasionally trichomonal infection.

Take a sample of vaginal discharge with a cotton swab from the vaginal wall or the vaginal pool, and place the swab in one to two drops of saline in a test tube. Keeping the sample warm will improve the yield for Trichomonas spp. because motility decreases at room temperature. Place the tube in warm water--or ask the patient to hold it while you complete the examination.

At the microscope, use your swab to place a drop of this saline solution on each of two clean glass slides. The first slide is the wet mount and will be ready to examine as soon as a glass coverslip is put in place. To the second slide, add one or two drops of 10 percent KOH solution, followed by a coverslip. The slide can be gently heated over a flame and allowed to rest for several moments before final evaluation. This will enhance cell lysis caused by the KOH and make the yeast forms more apparent. If no flame is available, waiting one to two minutes before reviewing the slide will allow more time for lysis. Begin at 10x power on the microscope to locate your sample plane, then increase to 40x for a closer view. Oil-field microscopy is not needed.

Immediately after adding KOH solution to your sample, sniff just above the slide. An obvious fishy odor indicates a positive whiff or amine test. Anaerobic bacteria release amine gas when treated with an alkaline solution. These bacteria are present in abundance in BV and, at times, trichomonal infection. The post-coital odor that is often described by women with BV occurs because ejaculate, like the KOH, is an alkaline solution.
How should vaginal infections be treated?

It bears repeating that 50 percent of women with vaginal symptoms do not have a definitive diagnosis. Because treatments for vaginal infections have side effects, these treatments should be used sparingly.

If you elect to treat BV, several regimens are available (Table 3).Topical vaginal applications of clindamycin or metronidazole gel are preferred by most women. Clindamycin can also be given orally. The traditional and cheapest approach is oral metronidazole twice a day for one week. However, the harsh taste, disulfiramlike reaction to alcohol, and dyspepsia all make this drug unpleasant for patients to take. In addition, its use in the first trimester of pregnancy is not recommended.

Cure rates are >90 percent for all of these medications, but recurrence is common. Six weeks after treatment for BV, up to 30 percent of women are again infected. Therefore, it is prudent to educate patients on the nature of this condition and to treat only those women who are symptomatic or have other indications for treatment, such as pregnancy. Alternative therapies, such as intravaginal yogurt, other antibiotics, treating partners, or douching with hydrogen peroxide, have all been tried and have not been proven to be clinically effective.

In mild-to-moderate candidal infections, single-dose oral therapy with 150 mg fluconazole is as effective as longer treatment regimens with either topical or other oral antifungals. Tissue concentrations persist in the therapeutic range for at least 72 hours following a single dose of oral fluconazole so that additional doses are generally not indicated. If there is significant vulvar inflammation associated with the yeast infection, topical antifungal therapy, such as clotrimazole, may be preferable to oral treatment.

Excellent cure rates for trichomonal vaginitis are. achieved with metronidazole, either 2 g orally in a single dose or 250 mg t.i.d. for seven days. Successful treatment is highly reliant on simultaneous treatment of male sexual partners, even if they are asymptomatic. In males, the seven-day course is more reliable than single-dose therapy. Again, do not use metronidazole during the first trimester of pregnancy.
What if a patient has recurrent symptoms?

Always repeat your diagnostic examination before treating any recurrent vaginal symptoms. Do not assume that the current symptoms are caused by the same pathogen as prior documented infections.

Look for an underlying cause for repeat or persistent infection. Bacterial vaginosis is a change in the vaginal ecosystem. Recurrence may be the norm, rather than the exception. Factors that may predispose to BV include trichomonal infection, irritant soaps, douches, and medications.

Candidal infection may recur in the setting of undiagnosed or poorly controlled diabetes. However, if the patient's blood sugar is well-controlled, other causes for recurrence should be explored. Immunosuppression from drugs or concomitant disease may be a factor. Women can help by wearing cotton underwear and loose-fitting clothes. Finally, although most yeast infections are due to Candida albicans, another yeast, Torulopsis glabrata, may be the culprit and can be identified by culture. Alternative therapies, such as boric acid, may be more effective for Torulopsis than the usual antifungals.

Trichomonal infection, as a sexually transmitted disease, may recur if the partner(s)--including women--are either untreated or insufficiently treated. Protected sex with condoms will prevent future infection.

When conventional treatment fails, consider alternative treatments--either a longer/higher dose or other therapy. For BV, options that have been shown to work, albeit not consistently, include high-potency metronidazole sponges, lactate gel, chlorhexidine suppositories, and povidone-iodine vaginal suppositories. Treatment of the sex partner has never been shown to reduce recurrence, but some physicians recommend abstention from sex for the duration of treatment.

Candidal vaginitis can be difficult to clear. Long-term oral or intravaginal suppressive therapy works, but high rates of recurrence can be expected as soon as suppressive therapy is discontinued. For less common yeasts, such as Torulopsis, boric acid suppositories intravaginally for 10 days are effective and may work for C. albicans as well. Recent evidence shows that daily eating of 8 oz of yogurt containing live Lactobacillus acidophilus reduces reinfection.

For patients whose initial treatment of Trichomonas spp. fails, retreatment with the same regimen is adequate. For recalcitrant trichomonal infection, continue therapy for 10-14 days with metronidazole. Clotrimazole, while rarely curative for Trichomonas spp., may relieve symptoms in women and can be used during pregnancy.
How should a pregnant patient be treated?

Bacterial vaginosis has been associated with premature rupture of membranes; postpartum endometritis; preterm labor; and postprocedural infections, such as those following termination of pregnancy. Treatment during pregnancy is indicated in symptomatic and asymptomatic patients.

Oral metronidazole, which is used in the treatment of trichomonal infection and BV, is contraindicated in pregnancy, particularly in the first trimester. If your patient is pregnant or considering pregnancy, use a topical vaginal preparation or, in the case of BV, use clindamycin.

Last updated Jan 4/07