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BV update: eliminating diagnostic confusion

In the absence of universally accepted data, 3 leading authorities review the evidence on bacterial vaginosis and discuss their approaches to diagnosing and treating this common vaginal affliction.

June 2002 · Vol. 14, No. 6
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The panelists

William Ledger, MD, is chairman emeritus and professor of OBG at the New York Weill Cornell Medical Center in New York City.

Sharon Hillier, PhD, is professor of OBG and reproductive sciences at the University of Pittsburgh School of Medicine in Pennsylvania.

Sebastian Faro, MD, PhD, is clinical professor of OBG and reproductive sciences at the University of Texas-Houston Health Science Center in Houston.

Key points

  • Physicians should not diagnose BV with a culture. A standard culture will not identify the number of anaerobic bacteria.
  • In diagnosing BV, an Ob/Gyn must perform a microscopic exam, along with a whiff test and pH.
  • Metronidazole and clindamycin are only 66% effective in treating BV.
  • Topical clindamycin causes a temporary overgrowth of E. coli and Enterococcus in the vagina.
  • Women whose vaginal microflora is colonized with hydrogen peroxide-producing Lactobacillus are less likely to acquire BV.
  • All women should be screened for BV during an annual exam.

The number one reason women visit their gynecologists is for the treatment of vaginal infections. Yet a recent Gallup survey found that only 36% had ever heard of bacterial vaginosis (BV), the most common type of vaginal infection, affecting 1 in 4 American women. BV is a disease caused by an overgrowth of anaerobic bacteria and Gardnerella, all of which can be found in low numbers in the healthy vagina. In fact, women who have been diagnosed with BV have up to 1,000 times more anaerobic bacteria than normal women.

Studies have shown that many women confuse the symptoms of BV with a yeast infection and often self-medicate with over-the-counter preparations. Unlike Candida, however, BV has been associated with pelvic inflammatory disease (PID), as well as an increased risk of endometritis, cervicitis, and in pregnant women, premature delivery. Therefore, it is imperative that Ob/Gyns properly diagnose and treat BV while creating greater awareness of the signs and symptoms of this widespread disorder among their patients. Here, Sebastian Faro, MD, PhD, William Ledger, MD, and Sharon Hillier, PhD, respond to OBG Management editors’ questions on appropriate diagnosis, screening, and management modalities to combat this potentially dangerous yet treatable condition.

OBG Management: How does a woman contract BV? What are the predisposing factors?

Dr. Ledger: In many cases, it is related to sexual activity, though there are certainly women who are not sexually active who can get it. Basically, there’s a change in the bacterial flora of the vagina. Unfortunately, what triggers that change is unknown.

Dr. Faro: I think an alteration in pH levels stimulates a change in the vaginal microflora. We don’t know what causes that, but this alteration stimulates other bacteria such as Gardnerella to grow. Frequency of sexual intercourse does affect the pH and flora.

Dr. Hillier: In following a group of women without BV over time, we have found that women who use douching products and those with greater levels of sexual activity are more likely to acquire BV. However, there are many women who are monogamous and who do not douche who acquire BV. In our studies, it turned out that women who had H2O2-producing Lactobacillus vaginally were significantly less likely to acquire BV1 (Figure 1). There is no way presently for a woman or her physician to tell whether the Lactobacillus colonizing the vagina produces H2O2. Nevertheless, we think that many women who acquire BV simply lack the most protective kind of normal flora.

OBG Management: If there is a positive whiff test when examining the patient, is it necessary to do a wet mount or a pH test?

Dr. Hillier: A positive whiff test indicates that there are high levels of anaerobic bacteria producing trimethylamine in the vaginal flora. In our experience, nearly every woman who has a positive whiff test will also have an elevated pH. It is still advisable to do a wet mount on a woman with a positive whiff test in order to evaluate for mixed infections with other agents such as Trichomonas vaginalis.

Dr. Ledger: Unfortunately, many physicians are trying to cut corners on things that are very simple to do. An Ob/Gyn cannot diagnose any vaginitis unless he or she knows how to do a microscopic exam, along with a whiff test and pH (Figure 2). The whole process takes seconds. If they are not doing these tests, they ought to be sending patients to someone who is.

Dr. Faro: I think it is critical to perform a microscopic analysis, a whiff test, and a pH. If you only rely on the whiff test, you often will miss BV. Individuals can have an elevated pH of 5, 5.5, or 6, and not have BV. This could signify a dominant flora with E. coli or some other bacteria. Furthermore, the Trichomonas patient will have a positive whiff test, a pH that’s 5 or greater, and not have BV.

OBG Management: How important is it to submit a Gram stain to the lab? Should a physician wait for these results to begin treatment?

Dr. Faro: Often, we’ll get back a diagnosis of BV on a Gram stain. I’ll then go back and find that these patients had a normal pH and large bacillary forms, which is in contradistinction to what the cytopathologist is reading. What this means is that Gram stains can be misread.

Dr. Ledger: The Gram stain is done when physicians don’t have microscopes in their offices. But there is a two-fold problem: the results come back a few days after the patient is seen, and there is a danger of misdiagnosis. I get a diagnosis of BV from a Gram stain at least once a week on patients who had normal pHs and didn’t have a positive whiff test. I think it may be identifying patients who have changes in their flora, but who don’t clinically have BV. Unfortunately, there are very few physicians who have microscopes or pH paper in their offices. Often, women will be treated for a yeast infection. In that situation, a Gram stain would be more useful. The bottom line is that every Ob/Gyn should have a microscope and pH paper at his or her disposal.

Dr. Hillier: I agree. The diagnosis of BV is best made using a microscopic exam of vaginal fluid, evaluation of pH, and the whiff test. However, if a microscope is unavailable or microscopy is not interpretable, a Gram stain of vaginal fluid can be a useful test for BV. Because the test needs to be sent to a central laboratory, it is not as practical as the wet mount, pH, and whiff test, but it does have good correlation with a well-performed clinical examination. If the results are in question following the clinical evaluation, it may be prudent to delay treatment until Gram stain diagnosis is available, which should take no more than 1 working day.

OBG Management: Who should be screened and when?

Dr. Faro: I think anyone who has any type of abnormality in the lower genital tract, including complaints of discomfort, burning, itching, and odor should be screened. In addition, a patient who is going to have gynecologic surgery or vaginal surgery should be screened. Also, I screen all gravidas, but not to prevent preterm labor. A gravida who has an abnormal flora and has a cesarean is at a greater risk of developing postpartum endometritis than a gravida who has a normal flora.2

Dr. Ledger: We screen almost everyone. Screening definitely should be done if the patient is complaining of abnormal discharge or has abnormal vulvar or vaginal findings.

Dr. Hillier: Women with symptoms of vaginal discharge or odor should always be evaluated for the presence of BV and other causes of vaginitis. Screening of asymptomatic women should be undertaken for those who are planning termination of pregnancy. Randomized, placebo-controlled trials have demonstrated that treatment of asymptomatic women with BV can reduce the incidence of post-abortal PID.3 There is a consistent relationship between BV and post-hysterectomy infections, which has lead some authorities to recommend routine screening of women before planned hysterectomy.4

OBG Management: Do you recommend BV screening during an annual exam? A recent study noted that approximately 50% of women with BV are asymptomatic.

Dr. Faro: Yes. I normally perform a pH test then. If the pH is 4 and she has no symptoms, I stop right there. If the pH is more than 4, I will progress to a whiff test and a microscopic examination of the discharge just to be certain. The dilemma is when you have a lady who may be totally asymptomatic with no complaints, and you find this abnormality in her vaginal flora. Should you treat or not treat? I tend to err on the side of not treating because an altered flora does not necessarily mean BV. One of the things we’re seeing a lot of lately is group B vaginitis, if such a thing exists.

Since there is a consistent relationship between BV and post-hysterectomy infections, some authorities recommend routine pre-hysterectomy screening.

Dr. Ledger: I agree. I also see something called desquamative vaginitis. In 40% of these women, the predominant organism is a group B streptococcus. So I’m not sure whether it’s desquamative vaginitis or group B strep. One of the realities is that we see all the patients who are not getting better with their first round of treatment.

OBG Management: Gravidas at 23 to 26 weeks’ gestation with BV are 40% more likely to deliver a low-birth-weight baby. If you find that gravidas have BV early in their pregnancy, how often do you screen them thereafter?

Dr. Ledger: I screen these patients every time I do a vaginal exam. But the problem is I’m not going to diagnose any patients who have asymptomatic BV because I don’t do a vaginal exam at every prenatal visit. Hoyme recommends that patients examine themselves twice a week. If they have an alkaline pH, they are to see the doctor right away. If the doctor confirms BV, they are treated.5 However, I think more studies are needed to determine whether twice-weekly screening is appropriate in the United States. Guidelines should not be established until we have some good data.

Dr. Faro: I also screen my patients every time I do a vaginal exam. As for twice-weekly screening, there has not been any research that has statistically shown a cause and effect between BV and preterm delivery (PTD). To come up with screening guidelines for something we aren’t sure is really causing a problem is not in our best interest. Furthermore, we really don’t have good treatments for these women. Metronidazole and clindamycin are only 66% effective, and they are a short-term treatment.6

OBG Management: Can you describe how BV causes preterm delivery?

Dr. Hillier: Although we understand that BV leads to an increased incidence of chorioamnion infection, placental inflammation, and amniotic fluid infection, the mechanisms by which BV causes preterm delivery are not completely understood. Failure to understand the pathophysiology of infection-related PTD has complicated these issues. Most women with BV deliver at term without complication. However, a really important question is why some women with BV deliver preterm. When we are better able to target the subset of women at increased risk—and offer them preventive treatment—I believe we will begin to see successes with clinical trials.

To normalize pH levels, prescribe Aci-jel and/or boric acid vaginal capsules or suppositories.

OBG Management: The current treatment for BV in gravidas and nonpregnant women is metronidazole and clindamycin. Because clinical studies have shown that these medications are not 100% effective, should physicians consider other agents? If so, what would these be?

Dr. Ledger: Certainly. The Europeans have come up with a number of alternate treatments that have lactobacilli in them. These are used to encourage the flora to get back to normal. I know there are researchers in the United States working on this, too. And Secundo Guaschino of Italy recently presented a paper at the seventh annual meeting of the International Infectious Disease Society of Obstetrics and Gynecology in which estrogen therapy for menopausal women resulted in a more normal flora dominated by lactobacilli. Of note, pretreated women with an absence of lactobacilli did not have BV.

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