People often talk about “getting tested for STIs” (sexually transmitted infections, also known as STD’s, sexually transmitted diseases). We ask partners if they’ve been “tested” and ask health care providers to run an “STI test.” But, we rarely think about exactly which tests we mean. So, how do STI tests work? Contrary to what “getting tested” implies, there is no one standard STI test panel. Different clinics may offer you different tests, depending on your background and their resources.
Advances in testing technology have made a large variety of tests available. Figuring out which tests to get can be confusing and overwhelming. Luckily, having lots of options means that your testing can be specific to your needs.
STI Test Sample Collection
First, it’s important to note that binx health does not require a urethral swab for any of our tests, and the only blood draw we request is a tiny finger prick. That means no swabs in penises, and no big needles! Now, let’s debrief the modes of sample collection that we do request, depending on the test you order:
- Urine Tests: Potentially the least intimidating of the sample collections. The standard “pee-in-a-cup” procedure is easy and gives us valuable information. At binx, urine collection is used for chlamydia, and gonorrhea screening in people with penises.
- Vaginal Swab: This form of sample collection is used for people with vaginas being tested for chlamydia, gonorrhea, trichomoniasis, or HPV.
- Anal Swab: This form of sample collection is used for people being tested for chlamydia or gonorrhea in their anus.
- Throat Swab: A swab of the back of the throat is used for people being tested for chlamydia or gonorrhea in their throat.
- Blood spot: A small finger prick by a device called a lancet is used to screen for syphilis, HIV, HSV/herpes, Hep B and Hep C. Once your finger is pricked, you will dab it on a small card that the lab will analyze.
All of these processes should be quick, relatively painless, and can be done wherever you are most comfortable. Feel free to reach out to us through email or chat and we’d be happy to offer further guidance on sample collection.
STI Test Sample Analysis
Across all STI testing providers, there is a wide variety of tests that can be run to determine whether or not you have an infection. Here are the most widely available tests:
DNA Replication: Urine samples, and urethral and endocervical swabs, are analyzed to detect small amounts of bacterial DNA through DNA replication techniques.
Bacterial Culture: Samples are collected through swabs of the urethra, vagina, cervix (Pap smear), anus and/or throat. The samples are placed in an environment where bacteria can grow, and then analyzed for bacterial growth.
DNA Replication: Urine or swab samples are analyzed to detect small amounts of bacterial DNA through the nucleic acid amplification test (NAAT).
Bacterial Culture: Samples are collected through swabs of the urethra, vagina, cervix (Pap smear), anus, and/or throat. The samples are placed in an environment where bacteria can grow, and then analyzed for bacterial growth.
Gram Staining: In people with penises who have symptoms, a discharge sample or a “first catch” urine sample (not peeing for at least an hour and then collecting just the first bit) is treated with dye that stains the walls of bacteria so they can be identified.
DNA Replication: Urine or vaginal swab samples are analyzed to detect small amounts of bacterial DNA through DNA replication techniques.
Parasitic Culture: Vaginal swab sample is placed in an environment where parasites can grow, and then analyzed for parasitic growth.
Microscope Analysis: Vaginal swab sample is analyzed under the microscope for the Trichomonas parasite.
DNA Replication: Vaginal/cervical swabs are analyzed to detect small amounts of HPV DNA through DNA replication techniques.
DNA Replication: Swab of a sore is analyzed for the herpes virus DNA.
Antibody test: Blood sample is analyzed for herpes antibodies.
Viral Culture: Swab of a sore is analyzed for the herpes virus.
Antibody test: Oral fluid or blood samples are tested for HIV antibodies.
Fourth Generation: Saliva or blood samples are tested for the HIV antigen and antibodies, allowing the test to detect infection sooner.
Nucleic Acid Amplification Tests (NAAT): Blood sample is tested for HIV. Results can be positive/negative or give an amount of HIV in the blood (“viral load”).
Non-Treponemal Test followed by Treponemal Test: A blood sample undergoes a non-treponemal test for antibodies produced in response to damage caused by syphilis bacteria and other diseases. If positive, then treponemal testing will be used to detect T. pallidum antibodies which are specifically produced in cases of syphilis.
Wondering how you could possibly collect these samples at home? Check out our blog on at-home testing to get some more answers.