# Self-Taken Vaginal Swab Tested by Nucleic Acid Amplification Detects More Chlamydia Infections Than Clinician-Obtained Endocervical Swab

 

 

      EBM Focus - Volume 8, Issue 1 

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Chlamydia is one of the most common sexually transmitted infections in women. Diagnostic samples may be obtained by clinicians during a pelvic examination, by urine sample, or by vaginal swabs taken by the patient. The optimal sampling method is unclear. A recent cohort study compared the diagnostic performance of self-taken vaginal swabs and clinician-obtained endocervical swabs for detection of C. trachomatis infection.

A total of 3,976 women ≥ 16 years old (35% asymptomatic) who were requesting testing for sexually transmitted infections took a self vulvovaginal swab prior to clinical examination. During examination, the clinician obtained an endocervical swab. Both swabs were tested using a nucleic acid amplification test (NAAT) designed to detect both chlamydia and gonorrhea. Any swab with a positive result of the first test was confirmed with a second NAAT specific for chlamydia. Chlamydia was diagnosed if either swab resulted in 2 positive test results.

C. trachomatis infection was detected in 10.3% of women. The detection rates were 97% for the self-taken vaginal swab and 88% for the clinician-obtained endocervical swab (p < 0.0001) ([level 1 \[likely reliable\] evidence](https://dynamed.ebscohost.com/content/LOE)). Subgroup analyses of both symptomatic women and asymptomatic women showed nearly identical results to the overall analysis ([BMJ 2012 Dec 12;345:e8013](http://www.ncbi.nlm.nih.gov/pubmed/23236032?dopt=Abstract)).

In a companion publication using the same samples and methodology, the two sampling approaches were compared for the detection of gonorrhea infections. Detection rates were 99% for self-taken vaginal swabs and 96% for endocervical swabs in overall analysis (not significant). In asymptomatic women, vaginal swabs had a 98% detection rate compared to 90% for the endocervical swabs ([BMJ 2012 Dec 12;345:e8107](http://www.ncbi.nlm.nih.gov/pubmed/23236033?dopt=Abstract&holding=caugamlib)).

For more information, see the [Chlamydia genital infection](http://search.ebscohost.com/login.aspx?direct=true&db=dme&AN=114223&site=dynamed-live&scope=site) and [Gonococcal cervicitis](http://search.ebscohost.com/login.aspx?direct=true&db=dme&AN=113822&site=dynamed-live&scope=site) topics in DynaMed.