What Does Negative STD Test Result After An Unprotected Sex Indicate?

Posted on Sun, 10 Aug 2014

Medically reviewed by Ask A Doctor - 24x7 Medical Review Team

Sun, 10 Aug 2014 Answered on

Tue, 2 Sep 2014 Last reviewed on

Question : Dear Doctor,
Last month I had a possible exposure to HIV in Spain when I had unprotected oral and vaginal sex with a Spanish masseuse (I was with her for about 2 hours). Between 9 and 10 days post exposure I had a Multiplex HIV-HBV-HCV PCR early detection test done and the results were Not Detected for HBV PCR, HCV PCR and HIV 1/2 PCV. I was advised that I could repeat this test for assurance and this I did. I had the Multiplex test repeated between 20 and 21 days post exposure and I have got the same results i.e. Not Detected. My tests for Syphilis. Gonorrhoea and C. trachomatis have also all been negative (these tests have also been done twice). The masseuse did say that she was in good sexual health. Do you think that I can regard the results of the tests as being conclusive? Many thanks for your help.

Answered by Dr. Praveen G (53 minutes later)

Brief Answer:
Yes the battery of tests are very much conclusive.

Detailed Answer:
Hello,
Welcome to Healthcare Magic,

As you have done all the lab investigations twice and they are very much negative, it definitely rule out the sexually transmitted infections (STIs) like Gonorrhoea, chlamydia and syphilis.

Viruses like Hepatitis B,C and HIV are detected by using a laboratory test called polymerase chain reaction (PCR). With this test a very small amount of the virus genetic material can be detected and measured.

PCR detects HIV virus in the blood as early as by 7 days following possible exposure. As you have tested between 9 and 10 days and between 20 and 21 days the test is negative. So you should not have HIV infection which is very much conclusive.

As HIV antigen detection by PCR is negative it confirms that you are not having HIV infection. I would suggest you to take precautions before indulging in sexual activity with unknown partners.

Thank you.

Above answer was peer-reviewed by : Dr. Raju A.T

Follow up: Dr. Praveen G (1 hour later)

Dear Dr XXXXXXX G,

Thank you very much for your answer.

You mention HIV antigen in your reply. However, the Multiplex PCR early detection test that I had was for the detection of HIV RNA. Does that in any way change your reply?

I will certainly take precautions in the future.

I look forward to hearing from you.

Many thanks for your help.

Answered by Dr. Praveen G (8 hours later)

Brief Answer:
PCR- HIV RNA reduces the window period

Detailed Answer:
Hello.
Thank you for the follow up query,

PCR- HIV RNA test will reduce the window period to less than two weeks. As you have repeated the test after 21 days of possible exposure and the result has come as negative suggest that you are not having HIV infection.

Thank you.

Above answer was peer-reviewed by : Dr. Bhagyalaxmi Nalaparaju

Follow up: Dr. Praveen G (3 hours later)

Dear Dr. XXXXXXX G,

Thank you for your follow-up reply.

Would you say that as the two tests that I have had done have both been negative for the HIV virus that it is conclusive that I do not have a HIV infection?

I look forward to hearing from you.

Thank you for your help.

Answered by Dr. Praveen G (1 hour later)

Brief Answer:
Yes

Detailed Answer:
Hello,
Thanks fo the follow up query,

It is very much conclusive. Donot bother about HIV infection.
Thank you.

Above answer was peer-reviewed by : Dr. Ashwin Bhandari