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The identification
of T. vaginalis in wet mount preparations of vaginal fluid is
strongly influenced by time.
"Shelf
life" of Trichomonas vaginalis.
Kingston MA, Bansal D, Carlin EM.
Int J STD AIDS. 2003;14:28-29.
Summary:
Question
How long after specimen collection can motile T. vaginalis be
identified in wet mount preparations of vaginal fluid?
Design
Wet mount preparations were performed immediately after collection from
female patients and then, for positive samples, every 10 minutes until
motile trichomonads could no longer be identified.
Participants
Among women undergoing testing for STIs in a genitourinary medicine clinic
in Nottingham, UK, 65 wet mount preparations of vaginal discharge were
positive for T. vaginalis.
Description of Tests and Diagnostic
Standard
A sample of vaginal fluid was taken from the posterior vaginal fornix with
a plastic loop, mixed with a fixed amount of normal saline on a microcope
slide, coverslipped, and examined immediately by dark field microscopy .
Those slides positive for trichomonads were re-read at 10-minute intervals
until the motile organisms could no longer be detected.
Main Outcome Measures
The amount of time, in 10 minute intervals, between the initial finding of
motile trichomonads in a vaginal fluid wet mount preparation and a
negative reading was determined for each sample.
Main Results
Ten minutes after the initial reading, 13 (20%) of the 65 positive samples
had become negative. The cumulative total at 30 minutes was 23 (35%)
samples. By two hours, 51 (78%) of the samples were negative.
Authors' Conclusions
One-fifth of all samples in which motile
trichomonads could be identified immediately after they were taken became
negative within 10 minutes of the initial reading. To maximize the
sensitivity of this method, all wet mount preparations of vaginal
discharge should be examined immediately after they are taken.
Source of funding:
None given
For correspondence: MA Kingston.
E-mail address: davemags@ntlworld.com.
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