Vaginal Swabs Are Non-inferior to Endocervical Swabs for Sexually Transmitted Infection testing in the Emergency Department

Abstract

Study Objective: Emergency department (ED) testing for sexually transmitted infections (STI) in women is typically performed with a pelvic examination and an endocervical swab. However, vaginal swabs are effective for STI testing and the preferred specimen type according to the US Centers for Disease Control and Prevention. The utility of using vaginal swabs in the ED for STI screening has not been thoroughly investigated. Our objective was to assess detection rates for two bacterial STIs before and after implementing a screening protocol using vaginal swabs. Methods: We conducted a quasi-experimental, pre-post study using standardized data from electronic health records across nine metropolitan Detroit hospital EDs. Patients included women who were tested for Chlamydia trachomatis or Neisseria gonorrhoeae in the ED between April 2018– December 2019. Pre-implementation tests from April 2018-February 2019 were done using endo-cervical swabs, and post-implementation tests from February 2019-December 2019 were done with vaginal swabs. We used non-inferiority testing for proportion with a non-inferiority margin of one percentage point absolute difference in detection rates of STI. Results: The study included 22,291 encounters with 11,732 in the pre-implementation and 10,559 in the post-implementation phases. The C. trachomatis detection rates were 7.5% pre-implementation and 7.6% post-implementation (between-group difference, 0.1 percentage points; 95% confidence interval [CI]: -0.7, 0.4; p<.01 for non-inferiority). The N. gonorrhoeae detection rates were 3.1% pre-implementation and 3.6% post-implementation (between-group difference, 0.5 percentage points; 95% CI: -0.8, 0.04; p<.01 for non-inferiority). Conclusion: Using vaginal swabs for STI testing in the ED may be a non-inferior alternative to using endocervical swabs

Sexually Transmitted Infections in the Emergency Department

“…44 Reliance on urine specimens as opposed to vaginal and endocervical swabs will result in ~10% fewer infections identified, [46][47][48] and result in many missed infections. 47,[49][50][51][52] Patients' self-collected vaginal swabs have comparable sensitivity to clinician-collected endocervical swabs, 51,53,54 and have been specifically found to be feasible and non-inferior to clinician-collected swabs in the ED environment. 55,56 Point-of-care (POC) tests are increasingly available (see Point of Care Diagnostics below) 57 For the diagnosis of TV, wet prep or wet mount microscopy is much less sensitive than NAAT.…”

“…Treatment is complicated by the need for prolonged treatment with multiple agents (Table 2). 48,[51][52][53][54]167,168…”

“…Studies show that STIs are missed when STI testing is limited to urine samples, a common practice in most EDs. [51][52][53][54] Further, extragenital sites may represent asymptomatic reservoirs for GC and CT. 44,161 The CDC now recommends that MSM should routinely be offered EGT when testing for a suspected STI. For heterosexual women, shared-decision making regarding EGT is recommended, based on the specific sexual history.…”