The Role of Physical Exam in Diagnosing Causes of Vaginitis
The Role of Physical Exam in Diagnosing Causes of Vaginitis
In this prospective cross-sectional study, diagnoses of common vaginal infections (TV, BV, VVC) made by SOVS were compared with diagnoses made by the combination of clinician obtained swabs (COS) and SE.
Women ages 18–45 years presenting with symptoms of abnormal vaginal discharge were recruited from an STI clinic in Baltimore, Maryland, USA, from March 2005 to August 2006 (figure 1). Exclusion criteria included abnormal vaginal bleeding, pregnancy and evaluation in the preceding 30 days for similar symptoms. Participants who met inclusion criteria and agreed to participate received a $10 gift card. All participants provided written informed consent. The institutional review boards of the Johns Hopkins Medical Institutions and the public health committee of Baltimore City Health Department approved this study.
(Enlarge Image)
Figure 1.
Flow chart for patient recruitment.
Participants completed a self-administered written questionnaire including information on demographics, medical, reproductive, contraceptive and sexual history and current vaginal discharge symptoms ( Table 1 ). After detailed instructions, each participant provided three SOVS. Each swab was inserted up to two inches into the vagina, rotated several times to sample the vaginal fluid and placed in its sterile container. The study recruiter collected the questionnaire and SOVS from the participants after unobserved sampling and processed the specimens according to the study protocol.
Self-obtained Vaginal Swabs Testing for SOVS including pH, preparation and interpretation of slides for microscopy of vaginal secretions in saline and 20% potassium hydroxide (KOH) and an amine odour ('Whiff') test was completed by the onsite laboratory technician using one swab. A second swab was used to prepare a dry slide for Gram staining, which was stored with the third swab for testing for GC, CT and TV.
Using Nugent's system, Gram stains are scored from 0 to 10 and assigned to one of three categories: normal (0–3), intermediate (4–6) and positive (7–10) for BV. Slides with a score of 7–10 were classified as positive for BV while 0–6 were classified as negative. The remaining SOVS and dry slide were collected twice a week and transported to an off-site laboratory for processing. GC and CT were tested by a US Food and Drug Administration approved strand displacement amplification assay (BDProbe Tec, Becton Dickenson (Franklin Lakes, New Jersey, USA). TV was tested from the same swab by research polymerase chain amplification (PCR) method in routine use at the Johns Hopkins University International STI laboratory. Testing was completed in weekly batches and all positive results were immediately distributed to clinicians.
Routine Clinical Assessment After providing the SOVS, participants were evaluated and managed according to clinic protocol which included pertinent history, physical examination, laboratory testing, treatment and referrals as needed. The physical examination included evaluation of the vulva/vagina, SE with collection of vaginal/cervical specimens and a bimanual examination. Standard laboratory evaluation for COS included point of care (POC) and delayed testing. POC testing included a vaginal swab used for pH determination and microscopy with saline and KOH slides and Whiff test for BV, VVC and TV diagnosis; and an endocervical Gram stain for the presence of inflammation and/or Gram-negative diplococci. Diagnosis of BV was based on Amsel's Criteria. TV required visualisation of the pathogen on wet mount. Centers for Disease Control and Prevention (CDC, 2010) define VVC diagnosis as based on vaginal discharge, irritation/pruritus, vulvovaginal oedema or erythema, pH and identification of yeast on KOH microscopy. Delayed testing consisted of an additional endocervical swab for GC culture and CT NAATs (Amplicor; Roche Molecular, Indianapolis, Indiana, USA). Women were treated based on the results of the POC testing. If the endocervical Gram stain demonstrated inflammation alone, the woman was presumptively treated for CT; if both inflammation and Gram-negative intracellular diplococci were present, she was treated for GC and CT. Delayed test results were assessed 48–72 h later; if a diagnosis of GC or CT was missed on the initial POC testing, the woman was appropriately treated. Furthermore, if testing for pathogens from the SOVS was positive (eg, TV), the woman was treated if she had not already received medication.
Reference Standards Gram stained smears prepared from the SOVS served as the reference standard for BV. The reference standard for TV was based on the research PCR method from the SOVS. The diagnosis of VVC rendered by the examining clinician and based on 2010 CDC criteria served as the reference standard for VVC. Wet mounts prepared from SOVS were tested by experienced onsite laboratory technicians. The examining clinicians (N=4) at the STI clinic trained in microscopy prepared and interpreted their own saline and KOH slides.
Qualitative Instrument After completing the SE, participants completed a self-administered qualitative questionnaire to assess their experience with SOVS versus SE. Using visual analogue scales, participants scored questions about their comfort with obtaining their own specimens, discomfort or pain with SOVS and SE, and preference of SOVS versus SE for evaluation of vaginal discharge. On a scale of 0–10 cm the visual analogue scale scored from easy to difficult, no pain to a lot of pain, very comfortable to very uncomfortable and not important to very important. For comparisons between the SOVS and SE, the former was placed at 0 and the latter at 10.
Diagnoses of Non-examining Clinician To identify the accuracy of SOVS, an infectious diseases clinician experienced in managing lower genital tract infections who did not examine the participants was asked to provide a diagnosis for TV, BV and VVC for each patient in the study based on history from the questionnaire and POC tests from the SOVS. This non-examining clinician diagnosed BV if participants were positive for at least two of three Amsel's criteria (pH>4.5, positive for clue cells>20% and Whiff test). TV was diagnosed by the presence of trichomonads on saline microscopy from SOVS. VVC was diagnosed based on the presence of yeast cells on wet mount, and the exclusion of other causes of vaginal discharge.
Sample Size Calculation Our prestudy estimate was that the per cent agreement between the diagnoses made by specimens collected by the SOVS and those collected by the COS would be 90%. The sample size of at least 138 women was based on per cent agreement between SOVS and clinician diagnoses of the common vaginal infections of BV, TV and VVC. This sample size allowed us to estimate the per cent agreement to within 5 percentage points with 95% confidence when the estimated agreement is 90% or greater (n=z1−α/2 (p0q0)/L).
Data Analyses Per cent agreement for the diagnoses of BV, TV and VVC is presented between the examining and non-examining clinician ( Table 2 ) and between clinicians and the reference standard ( Table 3 ). McNemar's test for bias, κ statistics and interpretation of κ are also reported. The reference standards included the diagnosis of BV based on the Gram stain prepared from the SOVS, TV diagnosed by PCR from the SOVS and VVC diagnosis rendered by the examining clinician. Total diagnoses for BV, TV and VVC were calculated based on the reference standard.
Methods
Study Design
In this prospective cross-sectional study, diagnoses of common vaginal infections (TV, BV, VVC) made by SOVS were compared with diagnoses made by the combination of clinician obtained swabs (COS) and SE.
Study Population
Women ages 18–45 years presenting with symptoms of abnormal vaginal discharge were recruited from an STI clinic in Baltimore, Maryland, USA, from March 2005 to August 2006 (figure 1). Exclusion criteria included abnormal vaginal bleeding, pregnancy and evaluation in the preceding 30 days for similar symptoms. Participants who met inclusion criteria and agreed to participate received a $10 gift card. All participants provided written informed consent. The institutional review boards of the Johns Hopkins Medical Institutions and the public health committee of Baltimore City Health Department approved this study.
(Enlarge Image)
Figure 1.
Flow chart for patient recruitment.
Data Collection and Laboratory Methods
Participants completed a self-administered written questionnaire including information on demographics, medical, reproductive, contraceptive and sexual history and current vaginal discharge symptoms ( Table 1 ). After detailed instructions, each participant provided three SOVS. Each swab was inserted up to two inches into the vagina, rotated several times to sample the vaginal fluid and placed in its sterile container. The study recruiter collected the questionnaire and SOVS from the participants after unobserved sampling and processed the specimens according to the study protocol.
Self-obtained Vaginal Swabs Testing for SOVS including pH, preparation and interpretation of slides for microscopy of vaginal secretions in saline and 20% potassium hydroxide (KOH) and an amine odour ('Whiff') test was completed by the onsite laboratory technician using one swab. A second swab was used to prepare a dry slide for Gram staining, which was stored with the third swab for testing for GC, CT and TV.
Using Nugent's system, Gram stains are scored from 0 to 10 and assigned to one of three categories: normal (0–3), intermediate (4–6) and positive (7–10) for BV. Slides with a score of 7–10 were classified as positive for BV while 0–6 were classified as negative. The remaining SOVS and dry slide were collected twice a week and transported to an off-site laboratory for processing. GC and CT were tested by a US Food and Drug Administration approved strand displacement amplification assay (BDProbe Tec, Becton Dickenson (Franklin Lakes, New Jersey, USA). TV was tested from the same swab by research polymerase chain amplification (PCR) method in routine use at the Johns Hopkins University International STI laboratory. Testing was completed in weekly batches and all positive results were immediately distributed to clinicians.
Routine Clinical Assessment After providing the SOVS, participants were evaluated and managed according to clinic protocol which included pertinent history, physical examination, laboratory testing, treatment and referrals as needed. The physical examination included evaluation of the vulva/vagina, SE with collection of vaginal/cervical specimens and a bimanual examination. Standard laboratory evaluation for COS included point of care (POC) and delayed testing. POC testing included a vaginal swab used for pH determination and microscopy with saline and KOH slides and Whiff test for BV, VVC and TV diagnosis; and an endocervical Gram stain for the presence of inflammation and/or Gram-negative diplococci. Diagnosis of BV was based on Amsel's Criteria. TV required visualisation of the pathogen on wet mount. Centers for Disease Control and Prevention (CDC, 2010) define VVC diagnosis as based on vaginal discharge, irritation/pruritus, vulvovaginal oedema or erythema, pH and identification of yeast on KOH microscopy. Delayed testing consisted of an additional endocervical swab for GC culture and CT NAATs (Amplicor; Roche Molecular, Indianapolis, Indiana, USA). Women were treated based on the results of the POC testing. If the endocervical Gram stain demonstrated inflammation alone, the woman was presumptively treated for CT; if both inflammation and Gram-negative intracellular diplococci were present, she was treated for GC and CT. Delayed test results were assessed 48–72 h later; if a diagnosis of GC or CT was missed on the initial POC testing, the woman was appropriately treated. Furthermore, if testing for pathogens from the SOVS was positive (eg, TV), the woman was treated if she had not already received medication.
Reference Standards Gram stained smears prepared from the SOVS served as the reference standard for BV. The reference standard for TV was based on the research PCR method from the SOVS. The diagnosis of VVC rendered by the examining clinician and based on 2010 CDC criteria served as the reference standard for VVC. Wet mounts prepared from SOVS were tested by experienced onsite laboratory technicians. The examining clinicians (N=4) at the STI clinic trained in microscopy prepared and interpreted their own saline and KOH slides.
Qualitative Instrument After completing the SE, participants completed a self-administered qualitative questionnaire to assess their experience with SOVS versus SE. Using visual analogue scales, participants scored questions about their comfort with obtaining their own specimens, discomfort or pain with SOVS and SE, and preference of SOVS versus SE for evaluation of vaginal discharge. On a scale of 0–10 cm the visual analogue scale scored from easy to difficult, no pain to a lot of pain, very comfortable to very uncomfortable and not important to very important. For comparisons between the SOVS and SE, the former was placed at 0 and the latter at 10.
Diagnoses of Non-examining Clinician To identify the accuracy of SOVS, an infectious diseases clinician experienced in managing lower genital tract infections who did not examine the participants was asked to provide a diagnosis for TV, BV and VVC for each patient in the study based on history from the questionnaire and POC tests from the SOVS. This non-examining clinician diagnosed BV if participants were positive for at least two of three Amsel's criteria (pH>4.5, positive for clue cells>20% and Whiff test). TV was diagnosed by the presence of trichomonads on saline microscopy from SOVS. VVC was diagnosed based on the presence of yeast cells on wet mount, and the exclusion of other causes of vaginal discharge.
Statistical Methods
Sample Size Calculation Our prestudy estimate was that the per cent agreement between the diagnoses made by specimens collected by the SOVS and those collected by the COS would be 90%. The sample size of at least 138 women was based on per cent agreement between SOVS and clinician diagnoses of the common vaginal infections of BV, TV and VVC. This sample size allowed us to estimate the per cent agreement to within 5 percentage points with 95% confidence when the estimated agreement is 90% or greater (n=z1−α/2 (p0q0)/L).
Data Analyses Per cent agreement for the diagnoses of BV, TV and VVC is presented between the examining and non-examining clinician ( Table 2 ) and between clinicians and the reference standard ( Table 3 ). McNemar's test for bias, κ statistics and interpretation of κ are also reported. The reference standards included the diagnosis of BV based on the Gram stain prepared from the SOVS, TV diagnosed by PCR from the SOVS and VVC diagnosis rendered by the examining clinician. Total diagnoses for BV, TV and VVC were calculated based on the reference standard.
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