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The use of lubricant
prior to specimen collection slightly decreased the sensitivity of
detection of C. trachomatis by PCR.
Does digital vaginal
examination using lubricant have an impact on testing of Chlamydia
trachomatis by polymerase chain reaction?
Uribasterra P, Creinin MD, Wiesenfeld
HC.
Sexually Transmitted Disease 2002;
29:112-113.
Summary:
Question
Does the use of lubricant during a vaginal examination decrease the
sensitivity of detection of C. trachomatis by PCR analysis?
Design
Comparison of C. trachomatis PCR results obtained from two
specimens collected from the same women before and after the use of
lubricant during a vaginal exam.
Participants
Forty-four nonpregnant women attending a hospital emergency department and
ambulatory care clinic, at least 18 years old, with positive test results
for chlamydia on routine screening by PCR testing, who had not yet been
treated. Exlusion criteria were use of an antibiotic or spermicide within
3 weeks of the original positive PCR test and a previous hysterectomy.
Description of Tests and Diagnostic
Standard
Two endocervical swab specimens were collected from each woman. The first
swab was collected after insertion of an unlubricated speculum. The
speculum was removed, a 3 g package of water-soluble lubricating jelly
containing no chlorhexidine was placed on a gloved hand for the pelvic
exam. The unlubricated speculum was reinserted and the second swab was
collected. Chlamydia PCR was performed according to the manufacturer's
instructions (Roche Diagnostics, Branchburg, NJ).
Main Outcome Measures
The concordance of the PCR results for the paired samples and the kappa
value of the observed concordance.
Main Results
Thirty-six of the 44 women were positive for C. trachomatis as
determined by the prelubricant PCR test. After examination with lubricant,
33 women had a positive PCR result, one of whom was negative for the
prelubricant test. A kappa value of 0.67 was determined from the observed
concordance rate of 89% (32 out of 36).
Authors' Conclusions
The use of a lubricant before specimen
collection affects the ability to obtain an adequate sample for PCR
analysis by producing no more than a 25% decrease in PCR sensitivity on
postlubricant samples, as compared with those obtained before digital
examination with lubricant.
Source of funding: Irene McLenahan
Young Investigator Research Award, Magee-Womens Hospital, Pittsburgh, PA.
For correspondence: None given.
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