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RNA testing after anal sex

Dec 9, 2007

After condom break during receptive anal sex 7 days ago with a partner of unknown hiv status, I am wondering how to proceed with testing. I am on PEP, started within 7 hours. Should I proceed with RNA testing at 12 days? I will certainly do the 6/18/36 week antibody testing. Should any of these times be altered because of PEP? Also, should I repeat RNA at 28 days? I have heard that such testing is fairly definitive. Is this true even with PEP?

Also, what about PEP? How many people actually seroconvert when taking PEP? I have not seen the statistics on this.

I am more worried about accuracy and getting quick answers than cost, and I am willing to risk the false positive to possibly get peace of mind.

Response from Dr. Frascino


HIV PCR RNA testing is not recommended for routine HIV screening. Period. It is particularly not recommended while on PEP! Think about it. PEP involves taking antiretroviral drugs. If you were HIV infected, taking antiretroviral drugs could drive HIV viral load (RNA) to undetectable levels. If you then try to use HIV PCR RNA as a screening diagnostic test you will get a false-negative result. As I have said numerous times before, HIV PCR RNA plasma viral load testing should not be used for routine HIV screening!

My advice is that you follow the published guidelines for post-PEP HIV testing. You can download a copy at

Finally, regarding efficacy of PEP and the number of people who seroconvert despite PEP, there are no statistics, as there are far too many confounding variables to consider, such as differences in PEP regimens, viral strains, interval of time between exposure and start of PEP, etc. Also, since we know PEP is at least partially effective, it would be unethical to do placebo-controlled clinical trials. What I can tell you is that PEP is not 100% effective. There are PEP failures despite starting immediately after an exposure and taking the medications as directed. (Yours truly is a prime example!) At this point you are doing everything you can. The odds remain very much in your favor. My only advice is to take your medications as directed and follow the recommended guidelines for post-PEP testing.

Good luck!

Dr. Bob

Dr Robert C Beck
you're so full of shit

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