Q: I’m trying to find accurate and consistent window periods for testing for various STDs as well as how long it takes to get results. Unfortunately, this information seems to be very hard to find at all and sometimes conflicting when I do find it. I know this will vary from state to state, clinic to clinic
Of greatest concern is the time it takes to get results. Please give me information for all the common STDs. Thanks.
A: Here are our best answers, broken down by disease.
> Chlamydia – standard used to be a bacterial culture (takes a few days to come back), but more common nowadays and more preferred for accuracy is a bacterial DNA PCR or SDA (both are types of NAAT). This can give results overnight. Both tests most commonly use urine samples. Window period is 2 days to 2 weeks.
> HPV – HPV testing done in the form of a visual inspection plus an application of acetic acid in a clinic can give you immediate results as to whether or not a lesion is HPV. This is the only way one can test for warts. Pap smears need to be read by a cytologist in a lab; depending on how busy your clinic’s lab is, this could take a few days or as long as two weeks to receive a result. Window period can be a few weeks to a few years; unfortunately, if someone gets an HPV outbreak or abnormal pap smear, it could be the result of HPV exposure from several years ago.
> Gonorrhea – same as Chlamydia. Time does not vary by specimen location per se; that said, some labs require a different collection tube for oral/throat specimens, and that can take a couple of extra days. Window period 2 days to 2 weeks.
> Herpes – visual inspection is the starting point, and suspicious lesions or rashes can be swabbed for viral culture. The culture takes a couple of days to grow in the lab, and may take an extra day for the lab to run typing on the viral DNA to distinguish between HSV I and HSV II. Blood Ab tests should take about a day to come back as reactive or not, and another day to run typing between HSV I and HSV II. Window period 2 days to 2 months; some people may contract HSV but never have obvious symptoms of an outbreak.
> HIV – we don’t have statistics about how many places use rapid tests vs. DNA tests; that said, in San Francisco, most clinics use rapid tests as a starting point to check for antibodies; any reactive test is confirmed with multiple Ab tests (Western blot and Elisa) and a PCR and/or a viral load. It is less common for clinics in this area to send tests to an outside lab for Ab. Ab and PCR tests should be available from a lab in a couple of days. Window period varies state-to-state; in California for antibody testing, it is 2 weeks to 6 months, with 98% of people developing antibodies 3 months after contracting HIV. DNA PCR tests are accurate 6 weeks after exposure.
> Syphilis – the blood test is an Ab test, either VDRL or RPR. Both of these take multiple steps: one to find an initial reactivity, and another to confirm that it is due to the syphilis bacterium. People with a history of syphilis infections will always test positive on the first step, so their specimens will always require multiple steps. The first step of this test can usually be completed in a day or two, with another day or two for subsequent steps on reactive specimens. Window period up to 2 months.
> Trichomoniasis – most clinics do not send specimens to outside labs for testing, though there is a culture available. Clinicians can diagnose trich off of a wet mount: a sample of discharge smeared onto a microscope slide examined in your doctor’s office. It is rare to test men for this infection, as they seldom have symptoms, but if a woman tests positive for trich she can request medication for her partners. Window period 1-2 weeks.
One thing we’d note about the more sensitive tests: they can sometimes be too sensitive and give false positive results. We have heard clients say that they test positive on a test, ask for a retest, and then show up negative. Also, depending on what lab your clinic or doctor’s office uses, test results may be delayed. We hear from local clinics that specimens they send to the local Department of Public Health Lab can take as long as 2 weeks to return results to them, but private labs may return results overnight. Your provider’s office may have either financial or contractual considerations as to which labs they use.
Reliable sources to get information about testing and window periods are:
http://www.labtestsonline.org/
http://www.ashastd.org/
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