Is A 4th Generation HIV Ab/ag Test Conclusive At 5 Weeks Post Exposure?

Posted on Thu, 16 Apr 2015

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

Thu, 16 Apr 2015 Answered on

Wed, 6 May 2015 Last reviewed on

Question : Hi there,
I got the 4th generation HIV ab/ag test done 5 weeks after a risky encounter. I have been told by my nurse that is good enough, but I am having trouble moving on, but the thought of taking another test gives me more anxiety. For that type of test, is 5 weeks post exposure enough time to give me a definitive result?

Answered by Dr. Bharatesh Devendra Basti (12 minutes later)

Brief Answer:
Conclusive after 12 weeks of exposure.

Detailed Answer:
Hi
Thank you for query. I am Dr Bharatesh D Basti answering your query.
Welcome to health care magic.
I have gone through the details and can make out your anxiety.

The chances of transmission of HIV by unprotected intercourse with HIV positive person is 1/200 to 1/1000. The risk is low. The person may be negative too.
It is good that the combo test is negative .
It detects both antigen and antibodies. Though the chances of tests coming positive later is almost nil, the conclusive test would be after 12 weeks for antibodies test.

You can get back for any clarification.
Thank you
Dr Bharatesh D Basti
Dermatologist and venerologist

Above answer was peer-reviewed by : Dr. Vaishalee Punj

Follow up: Dr. Bharatesh Devendra Basti (27 minutes later)

Thank you very much for the response. I do think that the majority of my anxiety is stemming from guilt. It was brief (less than 20 seconds) unprotected vaginal intercourse with a male I didn't know very well, no ejaculation. I understand my odds are very, very low, and with the combo test being negative, I should be fine, but anxiety works in crazy ways. Anyway, would you recommend to your patients retesting at 12 weeks to be sure? I have read that the chance of a false positive on a retest is higher than the chances of having contracted HIV.

Answered by Dr. Bharatesh Devendra Basti (55 minutes later)

Brief Answer:
Better to go for test after 12 weeks to be sure

Detailed Answer:
Hi
Thank you for follow up query.
The risk is almost nil with the given description.
It is better to go for antibodies test after 12 weeks to be sure .
The possibility of false positive results does not depend on previous test results(retest). The chances of false positive will be less than 1%.
You can get back for any clarification.
Thank you
Dr Bharatesh D Basti

Above answer was peer-reviewed by : Dr. Prasad