From the Guidelines
The use of High Vaginal Swabs (HVS) and Endocervical Swabs is guided by the location and type of infection, with HVS used for opportunistic vaginal infections and Endocervical Swabs used for sexually transmitted infections (STIs) like Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Mycoplasma, as these pathogens predominantly infect the endocervix. The rationale for this approach is based on the anatomical site where the infection is most likely to be present, increasing diagnostic accuracy and guiding proper treatment 1.
Types of Infections and Swabs
- High Vaginal Swabs (HVS) are used for opportunistic infections of the vagina, such as bacterial vaginosis, candidiasis, and trichomoniasis, as well as some STIs if the infection has spread significantly into the vaginal canal.
- Endocervical Swabs are specifically used for STIs like Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Mycoplasma because these pathogens predominantly infect the columnar epithelial cells of the endocervix rather than the vaginal epithelium.
Diagnostic Testing
- Endocervical samples are processed using Nucleic Acid Amplification Testing (NAAT), which is highly sensitive and specific for detecting the genetic material of these pathogens, even in small quantities 1.
- NAATs are preferred for C trachomatis detection in adolescents and young adults, regardless of symptoms, and are licensed for use with urine, urethral, vaginal, and cervical specimens 1.
Specimen Collection and Transport
- The optimal specimen types for chlamydia NAAT are female vaginal swab specimens and male first-void urine 1.
- Female urine remains an acceptable chlamydia NAAT specimen but may have slightly reduced performance compared with cervical or vaginal swab specimens 1.
- The transport and storage of specimens are crucial to ensure the accuracy of diagnostic tests, and laboratories should follow specific guidelines for handling and processing specimens 1.
From the Research
Rationale for Using High Vaginal Swabs and Endocervical Swabs
- High vaginal swabs are used for opportunistic infections of the vagina and some STIs if the infection is large enough to come down into the vagina 2, 3, 4, 5, 6
- Endocervical swabs are used for STIs such as Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Mycoplasma genitalium because the infection predominantly sits in the endocervix 2, 3, 4, 5, 6
Sensitivity and Specificity of Vaginal Swabs and Endocervical Swabs
- Vaginal swabs have been shown to have high sensitivity and specificity for detecting CT and NG, with sensitivities ranging from 82.6% to 100% and specificities ranging from 94.7% to 100% 2, 3, 4, 5, 6
- Endocervical swabs also have high sensitivity and specificity for detecting CT and NG, with sensitivities ranging from 88.6% to 95.5% and specificities ranging from 94.7% to 99.7% 2, 3, 4, 5, 6
Comparison of Vaginal Swabs and Endocervical Swabs
- Vaginal swabs have been shown to be superior to endocervical swabs for detecting CT and NG in some studies, with higher sensitivities and specificities 2, 4, 6
- However, other studies have found that endocervical swabs are equally effective as vaginal swabs for detecting CT and NG 3, 5
Nucleic Acid Amplification Testing (NAAT)
- NAAT is a highly sensitive and specific method for detecting CT and NG, and can be used on vaginal swabs, endocervical swabs, and first-void urine samples 2, 3, 4, 5, 6
- NAAT has been shown to be effective in detecting CT and NG in a variety of settings, including clinical and non-clinical settings 2, 3, 4, 5, 6