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The liquid-based
Pap smear is a specific method for the detection of T. vaginalis.
Accuracy of
detection of Trichomonas vaginalis organisms on a
liquid-based Papanicolaou smear.
Lara-Torre E, Pinkerton JS.
Am J Obstet Gynecol. 2003;188:354-356.
Summary:
Question
What is the performance of the liquid-based Pap smear compared to culture
for the detection of T. vaginalis?
Design
This study describes a direct comparison between the liquid-based Pap
smear and culture for the detection of T. vaginalis infections in
women who required a Pap smear.
Participants
Two hundred three consecutive patients seen in an urban women's health
center who required a Pap smear were tested. Fifty-six percent of the
women were pregnant, 42% reported a vaginal discharge, and 61% had a
history of previous STDs.
Description of Tests and Diagnostic
Standard
Patients had a Pap smear with the standard liquid-based method, followed
by a cervicovaginal swab for T. vaginalis culture using the InPouch
TV method (Biomed Diagnostics). A wet mount of vaginal fluid was performed
on patients who were symptomatic for vaginal discharge, itching, or odor. T.
vaginalis organisms seen on the Pap smear were noted on the report.
Cultures were observed daily for 5 consecutive days or until positive.
Main Outcome Measures
The sensitivity, specificity, positive predictive value (PPV), and
negative predictive value (NPV) of the liquid-based Pap smear compared to
culture for the detection of T. vaginalis were calculated.
Main Results
Forty-four (21.6%) of 203 women were positive for T. vaginalis by
culture. Sixty- three (31%) patients had a wet mount, of which 13 (20%)
showed T. vaginalis. T. vaginalis was reported in the Pap smear
result for 28 (13.8%) patients. The performance of wet mount and Pap smear
among symptomatic and asymptomatic women, compared to culture is shown in
the table.
Authors' Conclusions
The presence of T. vaginalis, as
stated by the liquid-based Pap smear pathology report, is highly specific
and warrants treatment without further testing, eliminating an office
visit to perform a confirmatory test. In asymptomatic patients, the Pap
smear detected T. vaginalis in 9.6% more women who otherwise would
not have had a test performed.
Source of funding:
Department of Obstetrics and Gynecology, University Hospitals of
Cleveland, Case Western Reserve University School of Medicine
For correspondence: Eduardo Laro-Torre,
Department of Obstetrics and Gynecology, University of Louisville, 550 S.
Jackson St., Louisville, KY 40202. E-mail address: elarotorre@yahoo.com.
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