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ORIGINAL RESEARCH |
From the Department of Obstetrics and Gynecology, Burns and Allen Research Institute, Cedars-Sinai Medical Center, Los Angeles, California.
Address reprint requests to: Neil S. Silverman, MD, Cedars-Sinai Medical Center, Department of Obstetrics and Gynecology, 8635 W. 3rd Street, Suite 160 West, Los Angeles, CA 90048; E-mail: silvermann{at}cshs.org.
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ABSTRACT |
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METHODS: Wet-mount screening examination of vaginal discharge was performed on all new patients seen at two resident-staffed clinics serving primarily indigent women. Leukorrhea was defined as >10 white blood cells per high-power field on microscopic examination; Amsel criteria were used to determine the presence of bacterial vaginosis, with a positive clue cell test result defined as >20% of epithelial cells. The diagnoses of C trachomatis and N gonorrhoeae infection were established by deoxyribonucleic acid amplification tests.
RESULTS: The study population consisted of 194 women, 118 (61%) of whom were pregnant. Overall, 11% of women had positive cultures for chlamydia or gonorrhea. Although both leukorrhea and clue cells were independently associated with positive cervical cultures, multivariate analysis found that clue cells did not contribute to the predictive value of leukorrhea alone among both pregnant (relative risk [R = 15.7) and nonpregnant (RR = 58.7) women. Negative predictive values for the screening test were comparably high (98–100%), independent of pregnancy status.
CONCLUSION: Leukorrhea, in the presence or absence of bacterial vaginosis, was strongly associated with cervical infections with C trachomatis or N gonorrhoeae among both pregnant and nonpregnant patients. In settings where patient follow-up is uncertain, on-site screening tests identify women for whom empiric antibiotic therapy for sexually transmitted diseases may be appropriate.
Infections with Chlamydia trachomatis and Neisseria gonorrhoeae remain major causes of morbidity among women, especially those of childbearing age. Approximately 12 million new cases of sexually transmitted diseases (STDs) occur annually in the United States. In 1997, there were over 200 new cases of chlamydia infection per 100,000 people, a rate exceeding that for all other reportable infectious diseases in the United States.1 In addition, 87% of the top ten communicable diseases reported to the Centers for Disease Control and Prevention (CDC) in 1995 were sexually transmitted diseases.1 This under-recognized epidemic has enormous health and economic consequences for women of all ages.
Women of childbearing age are at particular risk for STD infection and subsequent complications. Many infections are asymptomatic and under-diagnosed, and their resulting adverse health effects, including pelvic inflammatory disease (PID), tubo-ovarian abscess, infertility, chronic pelvic pain, and ectopic pregnancy can occur years after the initial infection. Among American women who suffer from infertility, for example, at least 15% can be attributed to complications of STDs, with up to 50% of these women unaware of their past exposure.2 In addition to these reproductive health issues, infection with chlamydia or gonorrhea during pregnancy has been associated with a variety of adverse outcomes, including premature rupture of membranes, chorioamnionitis, and postpartum infection.3
In the past, STD treatment goals have been particularly difficult to attain in settings serving more transient, lower-socioeconomic-group patient populations, who may also have a higher intrinsic risk of infection.4 Poor compliance and inconsistent follow-up after the initial clinic visit limits adequate assessment of treatment efficacy. Therefore, a rapid, sensitive, on-site screening test for cervical STDs would be a valuable adjunct to complete obstetric/gynecologic care for these women, allowing a focused point-of-service approach to management of this issue.
Working with a high-risk, transient population of primarily adolescent/young-adult inner-city women, we sought to assess the utility of easily recognizable microscopic components of vaginal secretions as a screening tool for the detection of cervical STDs. In addition, because some authors and clinicians have described a relative leukorrhea of pregnancy5,6 we examined wet mounts from both pregnant and nonpregnant women in this setting to determine the following: 1) whether microscopic detection of leukorrhea or bacterial vaginosis identifies a group of patients at high-risk for cervical infection with C trachomatis or N gonorrhoeae, and 2) if pregnancy alters the predictive value of those findings compared to those for nonpregnant patients.
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MATERIALS AND METHODS |
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All new patients undergoing routine pelvic examinations and baseline cervical cultures also had wet-mount examination of vaginal discharge performed by the obstetrics and gynecology resident staff. Deoxyribonucleic acid (DNA) amplification tests were used to diagnose cervical infection with C trachomatis and N gonorrhoeae (LCx STD Swab System, Abbott Laboratories, Abbott Park, IL). A cotton swab was used to obtain vaginal secretions or discharge with placement into both normal saline and potassium hydroxide solutions for microscopic evaluation. For saline evaluation, the swab was placed into a prepared test tube containing 0.2 mL of normal saline solution. One drop of the suspension was applied to a glass slide and examined at 400x via light microscopy. Potassium hydroxide evaluation was performed by mixing one drop of potassium hydroxide on a glass slide with secretions from a separate vaginal swab and examining microscopically. Leukorrhea was defined as >10 white blood cells per high-power field on microscopy.7 Amsel criteria, including three of the following four findings, were used to determine the presence of bacterial vaginosis on saline wet mount: a pH of >4.5, a positive whiff test, >20% clue cells, and a homogeneous discharge.8 Clinical findings regarding discharge type, presence or absence of mucopurulent cervicitis, pelvic pain, and cervical friability were recorded by residents on a standardized data collection form. Information regarding discharge pH, whiff test results, and wet-mount findings was recorded on a standardized data collection form. Results of cervical cultures for C trachomatis and N gonorrhoeae were later abstracted from the patients’ charts.
Categorical variables were examined using 
2 analysis with Yates correction, and continuous variables were analyzed with nonparametric testing as appropriate. Means are expressed plus or minus the standard deviation, and statistical significance is defined at the P < .05 level. Odds ratios (OR) and relative risks (RR) are expressed as appropriate. After performing univariate analyses, multivariate logistic regression analysis was used to construct an equation to adjust for potential confounding and effect modification. The data sets were created and analyses performed using Epi-Info 6 (CDC, Atlanta, GA).
Sample size calculation was based on an assumption that leukorrhea would be more difficult to diagnose among pregnant women and that the sample would be comparably divided by pregnancy status. Therefore, more conservative estimates were used for the calculation assumptions, and the derived sample size doubled to account for both pregnant and nonpregnant women. We assumed that 10% of women screened would have a positive screening test (office microscopy test for leukorrhea) and that the incidence of disease (a positive cervical culture) would be 5% in the screen-negative population and 50% in the screen-positive population. For a .05 two-sided significance level and a power level of 80%, 76 patients were determined to be necessary to detect that difference in group proportions, which led to a total desired study population of 152 women.
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RESULTS |
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. The overall rate of cervical infection, the primary outcome measure for this study, was 11% (10/194); only one woman was infected with gonorrhea alone, and four women (2%) were co-infected with both chlamydia and gonorrhea. Table 1 demonstrates that, except for patient age, there were no important differences in the patient characteristics studied between pregnant and nonpregnant women.
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, with a positive culture result for either C trachomatis or N gonorrhoeae defined as the outcome variable of interest. For the purposes of this analysis, vaginal pH was redefined as a dichotomous variable using 4.5 as a cutoff and "alkaline pH" defined as a vaginal pH > 4.5. Aside from age and pregnancy, all other patient characteristics identified were seen to be associated with an increased risk of a positive culture result. Patients with leukorrhea, in particular, were shown in this univariate analysis to be 124 times more likely to have a positive cervical culture than those without that characteristic; the presence of clue cells conferred a six-fold increase in risk of cervical infection.
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). Amsel criteria would not have been more helpful than clue cells alone in defining the overriding contribution of leukorrhea for the prediction of a positive cervical culture. Therefore, the presence of clue cells in the absence of leukorrhea could not be considered to be an independent risk factor for cervical infection.
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This revised model showed that among nonpregnant women, those who had leukorrhea were 58.7 times more likely to have a positive culture result than women without leukorrhea (11/12 [91.7%] versus 1/64 [1.6%], P < .001; RR = 58.7 [95% confidence interval (CI) 8.3, 413.2]). Among pregnant women, leukorrhea was still associated with an increased risk of a positive cervical culture, although the relative risk could not be calculated (9/15 [60%] versus 0/103 [0%]; P < .001). Because in our study population the majority of the positive cervical cultures were for chlamydia alone, the data were also examined using a positive chlamydia culture as the outcome variable. Leukorrhea remained a strong predictor of chlamydial infection in this model among both non-pregnant women (RR = 58.7; 95% CI 8.3, 413.2) and pregnant women (RR = 15.7; 95% CI 7.7, 32.2).
Comparing pregnant and nonpregnant women, both the sensitivity (100% versus 92%, respectively) and specificity (95% versus 98%) of leukorrhea for predicting cervical infection were comparable. The positive predictive value for leukorrhea, however, was higher among nonpregnant patients (92% versus 60%), whereas the negative predictive value of leukorrhea for both groups was similarly high (100% for pregnant and 98% for nonpregnant patients).
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DISCUSSION |
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Current screening tests used to detect cervical infection with STDs include microbiologic and cell cultures, direct immunofluorescent antibody assays, enzyme immunoassays (EIAs), and DNA probes. More recently, nucleic acid amplification tests have become increasingly employed, because they have been shown to have sensitivity and specificity rates of 99% and 90%, respectively.9,10 The barrier encountered with most of these diagnostic tests, however, is that they require at least 24–48 hours to yield results. Although the EIA for chlamydia requires only 30 minutes to complete, most studies indicate that the sensitivity of the EIA is only 60% when used in populations with an infection rate of at least 6%.11 In addition to their poor sensitivity, EIA tests are not suitable for processing large numbers of patient samples because they are labor intensive and cannot be automated.
In an attempt to avoid these commonly encountered problems associated with current screening methods, a number of investigators have explored the predictive value of a variety of vaginal markers of cervical infection. Moscicki et al12 found that <10 white blood cells per high-power field on a Gram stain of cervical secretions was 98% accurate in identifying the absence of C trachomatis when compared with culture results. In another study, Bohmer et al13 studied a population of pregnant women and found that the absence of leukorrhea on wet mount could accurately predict the absence of cervical chlamydia and gonorrhea infection. Others have postulated that bacterial vaginosis may be a marker for cervical STD infection, with the thought that the increased prevalence of anaerobic bacteria in the vagina may predispose certain women to develop upper genital tract infections with C trachomatis and N gonorrhoeae.14,15
Our study evolved as an extension of some of these earlier studies, hoping to confirm the strong predictive values of negative test results. In addition, and even more importantly for women at highest risk for STD infection, we attempted to evaluate the positive predictive value of rapid, on-site screening tests for cervical STD infection. Our results clearly demonstrate a powerful association between microscopic leukorrhea in particular and infection with either C trachomatis or N gonorrhoeae in a cohort of high-risk, inner-city women. The predictive value of these readily available, in-office tests were slightly affected by pregnancy status, with a lower positive predictive value for leukorrhea in pregnant compared to nonpregnant women (60% versus 92%). The high negative predictive value of this screening test was unaffected by pregnancy status, however (100% versus 98%). In addition, the high relative risk of cervical infection demonstrated in the presence of leukorrhea independent of pregnancy status supports the utility of office microscopy as a screening test for a high-risk population with unpredictable compliance with follow-up visits.
In such populations, like ours, a "diagnose-and-treat" protocol employing wet mount examinations could attempt to identify up to 75% of women with cervical STDs at the time of initial visit. In addition, in health care settings with limited resources, our results suggest that a negative office test for both leukorrhea and clue cells could predict the absence of STD infection with 92–99% accuracy, suggesting the option of not utilizing more expensive diagnostic tests if cost and payment are significant issues. Further cost–benefit studies may help to better define the value of such targeted testing protocols.
The majority of the cervical infections identified in this study population were due to chlamydia rather than gonorrhea, suggesting that empiric treatment based on screening tests might be best targeted against that single agent. A larger study might have permitted accrual of a larger number of women with gonococcal infection as well. Still, the sample size of our study population surpassed our initial power calculation assumptions, with 99% power to detect the differences we had proposed based on stratification by pregnancy and the presence or absence of leukorrhea. Moreover, the fact that gonococcal infection was still identified in this population, even at low levels, would seem to warrant single-dose treatment targeted against both agents in this high-risk cohort if leukorrhea is identified on screening. Testing of outcomes stratified by individual infectious agents might be warranted in evaluations of the screening tests in more compliant patient populations; in our less-compliant patient population, however, we chose to use a test result positive for either organism as the primary outcome variable.
In summary, we have demonstrated that in-office wet mounts may serve as sensitive, rapid screening tests that could help eliminate the problems associated with non-compliance and poor follow-up in high-risk, transient populations. Therefore, in settings where follow-up may be uncertain, these inexpensive on-site screening tests, particularly for the presence of leukorrhea, appear to identify women for whom empiric antibiotic therapy may be appropriate.
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Footnotes |
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Received December 12, 2001. Received in revised form April 16, 2002. Accepted May 13, 2002.
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REFERENCES |
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2. Eng TR, Butler WT. The hidden epidemic: Confronting sexually transmitted diseases. Washington, DC: National Academy Press, 1997.
3. Romero R, Mazor M. Infection and preterm labor. Clin Obstet Gynecol 1988;31:553–84.[Medline]
4. Katz BP, Zwicki BW, Caine VA, Jones RB. Compliance with antibiotic therapy for Chlamydia trachomatis and Neisseria gonorrhoeae. Sex Transm Dis 1992;19:351–4.[Medline]
5. McGregor JA, French JI. Bacterial vaginosis in pregnancy. Obstet Gynecol Surv 2000:55:1–19.[Medline]
6. Cunningham FG, Gant NF, Leveno KJ, Gilstrap LC, Hauth JC, Wenstrom KD, eds. Williams’ obstetrics. New York: McGraw Hill, 2001:221–47.
7. Eltabbakh GH, Eltabbakh GD, Broekhuizen FF, Griner BT. Value of wet mount and cervical cultures at the time of cervical cytology in asymptomatic women. Obstet Gynecol 1995;85:499–503.[Abstract]
8. Amsel R, Totten PA, Speigel CA, Chen KC, Eschenbach D, Holmes KK. Non-specific vaginitis: Diagnostic techniques and microbial and epidemiologic associations. Am J Med 1983;74:14–22.[Medline]
9. Rome ES. Sexually transmitted diseases: Testing and treating. Adolesc Med 1999;10:231–41.[Medline]
10. Bass CA, Jungkind DL, Silverman NS, Bondi JM. Clinical evaluation of a new polymerase chain reaction assay for detection of Chlamydia trachomatis in endocervical specimens. J Clin Microbiol 1993;31:2648–53.
11. Centers for Disease Control and Prevention. Chlamydia screening: A new HEDIS measure important to your members [fact sheet]. Atlanta, GA: Centers for Disease Control and Prevention, 2000.
12. Moscicki B, Shafer M-A, Millstein SG, Irwin CE Jr, Schachter J. The use and limitations of endocervical Gram stains and mucopurulent cervicitis as predictors for Chlamydia trachomatis in female adolescents. Am J Obstet Gynecol 1987;157:65–71.[Medline]
13. Bohmer JT, Schemmer G, Harrison F, Kreft W, Elliot M. Cervical wet mount as a negative predictor of gonococci-and Chlamydia trachomatis-induced cervicitis in a gravid population. Am J Obstet Gynecol 1999;181:283–7.[Medline]
14. Soper DE, Brockwell NJ, Dalton HP, Johnson D. Observations concerning the microbial etiology of acute salpingitis. Am J Obstet Gynecol 1994;170:1008–14.[Medline]
15. Eschenbach DA, Hillier S, Critchlow C, Stevens C, De-Rousen T, Holmes KK. Diagnosis and clinical manifestations of bacterial vaginosis. Am J Obstet Gynecol 1988; 158:819–28.[Medline]
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  W M Geisler, S Yu, M Venglarik, and J R Schwebke Vaginal leucocyte counts in women with bacterial vaginosis: relation to vaginal and cervical infections Sex Transm Inf, October 1, 2004; 80(5): 401 - 405. [Abstract] [Full Text] [PDF]
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