Our study demonstrated that a POC test for T vaginalis
(a rapid antigen test using lateral flow technology), performed on self-obtained or clinician-obtained vaginal swabs was more sensitive than wet mount and equal to culture. In addition, we showed that young women can accurately perform a simple POC STI test and interpret their own results. In our previous work we used latent class analysis to confirm the 100% specificity of the POC test.7
Therefore, the two apparent ‘false positive’ self-POC tests are most likely to represent a sampling error: the woman may have obtained a better sample than the clinician. However, there is also the possibility that the test is not truly 100% specific.
Our findings have two main implications for addressing the epidemic of STI that disproportionately affects young women. First, we have demonstrated that self-obtained vaginal specimens were feasible and reliable for the diagnosis of trichomoniasis using a POC test. Others have demonstrated that self-collected vaginal swabs perform well in detecting chlamydia and gonorrhoea using NAAT11–13,22
and trichomoniasis using culture and/or PCR.14,16
The use of self-obtained vaginal specimens for the diagnosis of STI using NAAT has been promoted by many researchers,23
as well as the CDC.24
We thus now have another diagnostic method that can reliably be used on self-obtained vaginal specimens.
Self-swabs remove the requirement for a speculum examination, a factor that deters both women from accepting and clinicians from offering STI testing. Adolescent women express a clear preference for non-invasive methods over a pelvic examination.25
Among adolescent women offered self-obtained vaginal swabs for STI testing in a school setting, the majority rated self-swabs as easy to perform and preferable to a pelvic examination, and half of those with a diagnosed STI said they would not have sought STI testing if self-collection was not offered.26
Therefore, for asymptomatic women for whom a speculum and full pelvic examination are not indicated, a self-obtained vaginal swab may be the specimen of choice to detect trichomoniasis, as has been recommended for chlamydia. In this study, we collected survey data assessing the acceptability of self-testing compared with clinician testing at baseline and after testing. However, this complex dataset is still being analysed.
Second, we have shown that women can accurately perform their own STI tests, especially a simple device based on familiar lateral flow technology. We could not find literature to assess whether women could perform a home human chorionic gonadotrophin test for pregnancy (also lateral flow technology) before it became available over the counter, but it is possible that this was considered market research and did not get published in the scientific literature. The only other over-the-counter self-test device available to women is a self-pH test (pHEM_ALERT, http://Gynex.com
, Redmond, Washington, USA). Before its release, two studies evaluated the pH test. The first used a questionnaire to assess whether adult women could understand the package insert, and 97.1% gave correct answers to at least 75% of the questions. In another study, pH results obtained by adult women were highly correlated with healthcare professional’s results (κ=0.9).27,28
Vaginal pH may be useful in distinguishing candidiasis from BV; however, while we and others have shown that abnormal pH is associated with trichomoniasis, pH is neither sensitive nor specific enough to use as a diagnostic tool for trichomoniasis or other STI.
If young women had access to a simple POC test for trichomoniasis, they could identify twice as many cases as a clinician could using the insensitive wet mount examination, and nearly as many as NAAT testing. In fact, many clinicians no longer perform the wet mount, as it requires a microscope and because of Clinical Laboratory Improvement Amendment regulations. POC testing also provides the patient with her results within minutes, allowing immediate counselling and treatment and reducing the risk of transmission and the proportion of women who are lost to follow-up. In addition, we have shown that women who are aware of their POC test results are more likely to report safer sexual behaviours in the weeks after diagnosis.29
These issues are especially important for adolescent women who may be concerned about confidentiality and have limited access to health care. Another potential use of this POC T vaginalis
test would be in resource-limited settings such as less developed areas of the world, where both diagnostic tests for trichomoniasis and access to pelvic examinations are limited.
A self-performed STI test would be a novel strategy to address barriers to STI testing in adolescent women. Gaydos et al30
recently demonstrated that adults can reliably perform their own HIV POC test in an ED setting. We believe we are the first to show that adolescent women can accurately perform and interpret an STI test. Unfortunately, intellectual property licensing may prevent over-the-counter marketing of this simple and effective tool. As other simple STI tests become available, we expect that our findings can be used to inform future decisions about the use of these tests by adolescent women.
If women could accurately perform a POC test for trichomoniasis in a clinical setting, they would avoid a pelvic examination, improve the accuracy over wet mount and receive immediate feedback that would allow treatment. Furthermore, self-POC testing could be expanded for use in non-clinical settings and even home use. In these scenarios, the convenience and confidentiality of self-testing may encourage more women to seek testing, thus impacting the overall epidemic of trichomoniasis in the USA.
► Self-obtained vaginal swabs are reliable specimens for POC trichomoniasis testing.
► Adolescent women can accurately collect and perform a POC test for trichomoniasis.
► Self-performed POC trichomoniasis tests were highly correlated with clinician-performed tests.
► Self-obtained and self-performed testing could eliminate barriers and increase STI testing in vulnerable populations.