Abnormal Vaginal Discharge: Using Office Diagnostic Testing More Effectively

AE_French.1004.final 9/20/04 3:18 PM Page 805 Applied Evidence N EW R ESEARCH F INDINGS T HAT A RE C HANGING C LINICAL P RACTICE Abnormal vaginal discharge: Using office diagnostic testing more effectively Linda French, MD Michigan State University, East Lansing, Mich Jennifer Horton, DO Genesys Regional Medical Center Family Practice Residency, Grand Blanc, Mich Michelle Matousek, DO Henry Ford Health System, Detroit, Mich Practice recommendations and effective treatment. (An article on treatment by the same authors will appear in next month’s ■ Accurate differential diagnosis for women issue of THE JOURNAL OF FAMILY PRACTICE.) complaining of abnormal vaginal discharge In a primary-care study,4 vulvovaginal symp- requires in-office diagnostic testing at mini- toms including vaginal discharge were due to vul- mum, and laboratory testing in selected cases. vovaginal candidiasis (VVC) in 27% of patients, bacterial vaginosis (BV) in 21%, trichomoniasis in ■ Test for Chlamydia trachomatis and 8%, Chlamydia trachomatis in 2%, Neisseria gonor- Neisseria gonorrhea when signs of rhea (GC) in 1%, and no infection in 34%. Several purulent cervicitis are present (SOR: B). pathogens may coexist.2 VVC, BV, and trichomoni- ■ In suspected vulvovaginal candidiasis, asis account for at least 90% of infectious vagini- culture is recommended for patients with tis.5 This review will therefore focus heavily on recurrent or persistent symptoms and a neg- these causes of vaginal discharge among women ative wet mount result (SOR: B); rapid slide of reproductive age, including pregnant women. latex agglutination testing is not better than ■ microscopy for diagnosing VVC (SOR: B). CERVICITIS AND PHYSIOLOGIC CERVICAL DISCHARGE Some women may interpret a physiologic increase n primary care practice, abnormal vaginal dis- in cervical mucous production as abnormal. It charge is a common complaint. Signs and occurs cyclically prior to ovulation, is typically Isymptoms of vaginitis—the most common transparent and colorless, and may be more pro- gynecologic diagnosis in primary care1—are not nounced in women with an everted cervix. specific for any single underlying cause.2 Office- based diagnostic testing, which is underused,3 Chlamydial infection must be employed to ensure accurate diagnosis In the clinical examination of the cervix, 3 char- acteristics have been associated with chlamydial infection: yellow endocervical discharge, easily Corresponding author: Linda French, MD, Associate Professor, induced cervical bleeding, and opaque cervical Department of Family Practice, College of Human Medicine, 6 Michigan State University, B101 Clinical Center, East discharge. All 3 findings are statistically Lansing, MI 48824. E-mail: [email protected]. significant and independently associated with OCTOBER 2004 / VOL 53, NO 10 · The Journal of Family Practice 805 AE_French.1004.final 9/20/04 3:18 PM Page 806 ABNORMAL VAGINAL DISCHARGE conditions such as pelvic inflammatory disease How to perform a wet mount (PID), postoperative infections, and pregnancy- related complications including prematurity. It To perform a wet-mount preparation correctly, dilute also increases the likelihood of acquiring HIV in the vaginal discharge with 1 or 2 drops of 0.9% saline women exposed to the virus.8,9 and place it on a slide. Examine the slide under low- Two principal factors put women at risk for and high-powered fields for vaginal squamous cells, acquiring BV: douching and exposure to a new white blood cells (WBCs), lactobacilli, clue cells, and sexual partner, both of which are thought to dis- 10 trichomonads. An increased number of WBCs can rupt the vaginal ecosystem. be defined as >5–10 WBC/HPF or WBCs exceeding the number vaginal epithelial cells. Relative benefits of diagnostic tests To prepare the potassium hydroxide (KOH) slide, A gold standard test has not been established for BV. In about 50% of asymptomatic women, cul- place a generous amount of vaginal discharge on a ture results are positive for flora such as slide with 10% KOH solution. Air- or flame-drying Gardnerella vaginalis.5 While Amsel’s criteria are before examination under low-power microscopy often used as a reference and generally suffice for may improve sensitivity. A positive KOH preparation the evaluation of symptomatic women, the best will have hyphae, mycelial tangles, or spores. candidate for a gold standard test is probably Gram stain assessment using Nugent’s criteria chlamydial infection (odds ratios 2.8, 2.3, and 2.9, (described in this section).11 Lack of leukocytes in respectively). In the primary care study cited the vaginal fluid supports a diagnosis of BV. A above, purulent cervical discharge was found in finding of white blood cells in excess of the num- 6% of women, most commonly testing positive for ber of vaginal epithelial cells suggests an inflam- Chlamydia, less often for GC.4 matory process (SOR: C).12 Trichomonas vaginalis may cause cervicitis as Amsel’s criteria with wet mount. The diag- well as vaginitis. Mycoplasma genitalium has been nostic approach most commonly used in the office proposed as an additional possible pathogen. It is Amsel’s criteria—homogenous discharge, posi- was identified in 7% of more than 700 women tive whiff-amine test, pH >4.5, and clue cells with mucopurulent cervical discharge seen in a found on wet-mount microscopy (see How to per- STD clinic with otherwise negative cultures.7 form a wet mount).13 Three of 4 criteria deemed With cervical discharge that appears to be puru- positive is considered diagnostic. If Gram stain is lent, testing is warranted as a minimum for used as the reference standard, then Amsel’s cri- Chlamydia and GC (SOR: B). Screening of asymp- teria have 70% sensitivity and 94% specificity for tomatic women less than 26 years of age for diagnosing BV.14 An analysis of the individual cri- Chlamydia is recommended by the US Preventive teria follows. The positive and negative predictive Services Task Force (SOR: A). values of each compared with the whole group as reference standard is displayed in Table 1. ■ BACTERIAL VAGINOSIS Homogenous discharge. A thin, homogenous, Bacterial vaginosis (BV) is neither an inflamma- grayish discharge is traditionally associated with tory condition nor an STD, but is a shift in vaginal BV. However, it is not specific to BV, being found flora from the normal condition in which lacto- commonly also in women with culture results pos- bacilli predominate, to a polymicrobial flora in itive for VVC or no diagnosis of vaginitis.2,15 It is which gram-positive anaerobes predominate. In the criterion least likely to be consistent with the addition to annoying vaginal symptoms, BV is whole group, seen in about half of women BV- associated with increased risks of more serious positive and over one third of women BV-negative 806 OCTOBER 2004 / VOL 53, NO 10 · The Journal of Family Practice AE_French.1004.final 9/20/04 3:18 PM Page 807 ABNORMAL VAGINAL DISCHARGE 15 using Amsel’s criteria as the reference standard. TABLE 1 Whiff test. The whiff test is performed by Predictive values of Amsel’s criteria adding drops of 10% potassium hydroxide solu- (using 3 of 4 positive as diagnostic tion to the vaginal fluid. A positive result is a reference standard) “fishy” amine odor. In a study16 of 100 women complaining of malodorous discharge, a positive Diagnostic criterion Predictive value (%) whiff test was predictive of positive culture Positive Negative results for anaerobic flora such as Bacteroides sp. Homogeneous 42 89 with sensitivity 67%, specificity 94%, and a posi- thin discharge tive predictive value of 95%. The whiff test was seen at introitus not positive in any of the 5 cases with positive cul- pH >4.5 53 94 ture results for G vaginalis in the absence of anaerobes. There were also 12 cases positive for Odor on 94 93 anaerobes without G vaginalis. alkalinization pH >4.5. Since the abnormal flora of BV is con- Clue cells on 90 99 sistently associated with a vaginal pH >4.5, a nor- wet mount mal pH excludes a diagnosis of BV.17,18 The deter- Source: Thomason et al 1990.15 mination of pH in the narrow range around 4.5 is not accurate using standard nitrazine paper. Narrower-range test paper is available and more 0 to 10 based on semi-quantitative assessment of accurate. Examples include pH paper for 4.5 to 5.5 3 classes of morphotypes (Table 2): large gram- (Micro Essential Laboratory), FemExam pH and positive rods (Lactobacilli), small gram-negative Amines Test Card (Litmus Concepts), pHem- rods (Gardnerella and Bacteroides spp.), and small ALERT: pH paper on a stick (Imagyn Gynecology). curved gram-variable rods (Mobiluncus spp.).11 Cervical mucous, semen, and blood are alkaline Diagnosis of BV is typically made when the and can interfere with pH testing. Estrogen pro- Nugent score is 7 or more, which appears qualita- duction is also necessary to maintain an acidic tively as dominant morphotypes other than environment. A pH of 3.8 to 4.5 is consistent with Lactobacilli. Gram staining is more objective and normal vaginal flora in premenopausal women reproducible compared with wet-mount examina- with normal estrogen production.17 tion, with a sensitivity of 93% and specificity of Clue cells. Clue cells are vaginal epithelial cells 70% if Amsel’s criteria are used as the gold stan- coated with coccobacilli giving an appearance as dard.14 It is useful for the evaluation of asympto- if coated with ground black pepper. Clue cells on matic women. It also provides a durable record of wet mount preparation is considered the most the patient specimen. Compared with Gram stain, accurate of Amsel’s diagnostic criteria for BV.19 On Amsel’s criteria tend to underdiagnose cases. We the other hand, office evaluation of the wet mount can expect that if screening for BV in pregnancy is considered by some authors to be unreliable becomes a recommendation, Gram staining in a due to dependence on the clinician’s microscopy clinical laboratory will be the recommended skills and lack of a durable record of the patient method of diagnosis.

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