Self-taking vaginal sample best test for chlamydia and gonorrhoea in women

The optimal diagnostic sample for Chlamydia trachomatis detection should detect the maximum number of infected people.  In women without symptoms the sample of choice is a self taken vulvovaginal swab, which can be done in the privacy of one’s home. But it is not clear whether a vulvovaginal swab or an endocervical swab is the optimum sample in women with symptoms requiring speculum examination.

A recent study by Sarah Shoeman and colleagues published in the BMJ compared the two sampling methods. They showed that in women attending a sexual health centre vulvovaginal swabs were significantly better at detecting chlamydia infection than endocervical swabs among women with symptoms of a sexually transmitted infection.

In these cases, using endocervical samples rather than vulvovaginal swabs would have missed 9% of infections, or 1 in 11 cases of chlamydia infection

A  parallel  study by the same group showed that self taken vaginal swabs tested by the  Nucleic acid amplification tests (NAATs) which offer increased sensitivity for detecting gonorrhoea, is significantly more sensitive and offers good specificity for detecting gonorrhoea compared with standard gonorrhoea culture methods.

However  confirmation of positive results with a second NAAT is essential in low prevalence populations such as the UK, to avoid false positive results

Women and clinicians can be confident that self taken vulvovaginal swabs are as accurate as clinician performed tests for the detection of chlamydia and gonorrhoea in women without symptoms and should be the test method of choice in asymptomatic women.

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