[Question #4247] Testing and advice

29 months ago
So here's the skinny....

I had unprotected vaginal sex 17 days ago with a girl who's status is unknown. She says she's clean and I like to believe her but anxiety has taken over

I tested negative for claymadia and gonarehea 6 days after exposure 

I am nervous about HIV. I am married and have not had unprotected sex with my wife  since the incident which is raising her suspicions 

My questions

Is the 4th gen test conclusive at 28 days or 42 days ( seems to be conflicting opinions)?

And outside of the false positive aspect chance, could I go get a PCR RNA HIV 1 and 2 test tomorrow so I can move on with my life sooner than waiting 2 to more 4 weeks. Would the RNA test at 2 plus weeks be conclusive?

I know the odds are in my favor but just need to put this behind me, thanks 
Edward W. Hook M.D.
Edward W. Hook M.D.
29 months ago
Welcome to the Forum.  I'll be glad to comment.  Most people do not have STIs, including HIV and following exposure to a partner with infection, most people do not get infected (typically less than 20-25%).  Thus the odds that you were infected are low.  That said, I understand your concern and think testing is reasonable.  Your tests for gonorrhea and chlamydia take at 6 days provide you with conclusive evidence that you were not infected. 

For HIV your risk for infection is somewhere in the range of less than 1 in a million.  Testing with currently available combination HIV antigen/antibody tests will provide conclusive results at 42 days after exposure (we used to say 28 days but a few later cases have been described.  That said a 4 week result will detect over 99% of recent infections).  Alternatively, a PCR test for HIV will be conclusive after 11-14 days after exposure.  There is a slightly higher (but still low - less than 1%) rate of false positive PCR tests but you will get your results sooner. 

Personally, at this time I would no longer be worried and would not be worried about abstinence from unprotected sex with your wife.  EWH
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29 months ago
Thanks doc for the very quick response.  You guys do a great job here

I guess my only follow up is if I go to do the RNA PCR test this week (18-20 days post exposure), I can be 99.9 % confident in the negative response and if I get a positive response (which could most likely be a false postitve), restest at 42 days with 4th gen DUO test?

I only ask because many things you read on the net seem to discourage the RNA test but those discourages seem to be with a false positive and not a false negative, correct? Thanks again 
29 months ago
Bump
Edward W. Hook M.D.
Edward W. Hook M.D.
29 months ago
You are correct.  With a negative PCR you can be entirely confident that you did not acquire HIV (i.e. more than 99.9% confident). 

You are also correct, we are not enthusiastic about PCR testing.  It is more expensive and as you mention there can be problems with false positive tests which can be very, very disconcerting while they are being sorted out.  If more and more people who are not at substantial risk go this route, there will be more and more false positives.   EWH
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29 months ago
Bump

May as well get my money's worth and ask a third question

Next Friday I have an appointment for my RNA HIV test. That will be 27 days after exposure. Will 27 days out still give me an accurate result on the RNA test.? They are testing for syphillis and herpes as well. Your input Dr?
Edward W. Hook M.D.
Edward W. Hook M.D.
29 months ago
Yes, a negative RNA test at 27 days will absolutely prove that you did not get HIV from the exposure you have described,  A syphilis test at that time will likewise rule of the possibility of syphilis.  We specifically recommend against blood tests for herpes unless there are lesions or a partner has a history of the infection as these tests have relatively frequent false positive test results and can be misleading.  Further unless you have HSV testing in the past, a positive test, if not false positive is more likely to indicate a previous infection that you did not know you had than to discover that you had acquired HSV from the exposure you describe.  Do you really want to open that can of worms- I advise against it.  EWH
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