Due to extreme worry and concern about exposure to HIV, I took PCR RNA quantitative at day 12. (The sensitivity of the pcr rna test that I took was 98%). I’m planning on taking the fourth generation test at day 28, and I saw you doctors saying that the combination of the tests will be conclusive 100%. 

My questions are as follow:

1) will the combination of the tests pcr rna and fourth generation be 100% conclusive? 

2)does the fact that the sensitivity of pcr rna test was 98% change the answer to the question above? 

3) I took the pcr rna at day 12 and fourth generation at day 28. Is that sufficient for them to be conclusive for hiv?

4) if the tests are not 100% conclusive, are they above 99.5% accuracy? Or, are they the equivalent of 99.5% or above sensitivity?

Thank you a lot doctors 

1.  Yes, for all practical purposes.   Please see my comments regarding test performance and what conclusive means from our earlier interaction. 

2.  No

3.  Yes

4.  They are conclusive.

I urge you to accept the FACT that you were not infected.  Please do your best to stop worrying and move forward.  EWH

I’m planning on taking the fourth generation test tomorrow, which would mean it would be taken at day 23 after exposure. If the test were negative, would this mean that the combination of the two tests are 100% conclusive. 

B) is taking pcr rna at day 12 and fourth generation at day 23 equivalent to taking fourth generation at day 42? 

I’m really concerned doctor that the test won’t be conclusive. 

Many thanks!!!

My cousin happened to work in the lab that performed the tests, and she told me that she performed the pcr test twice, using two different machines with different sensitivities (rotor gene with 98.2% sensitivity and genexpert with 98.9% sensitivity ) now I understand that the probability of my test being false negative is 1.8% and 1.1%. My questions are as follow: 

1) when agencies say that their tests have a certain sensitivity, is that because of something wrong in the blood sample (that would be concerning) or is it because of technical issue ( from the test itself or the person doing the test)? In other words, does the fact that my cousin performed the pcr test twice using two different machines make my test more reliable? 

2) given that she did the test twice using two different machines with different sensitivities, can I now consider the overall sensitivity to be above 99.7% ?

3) my cousin told me she was extremely careful doing the test, and the results were quite clear, does that make the test more reliable? In other words, when agencies say the test has a certain sensitivity, is it because they anticipate an error from the test itself or because error with the sample? 

4)lastly, can I consider myself lucky that my cousin did the test twice? Would you say that the accuracy of my two tests are above 99.5%? 

Straight to your questions:

1.  Published sensitivity estimates are the results of large clinical trials which test both positive and negative specimens.  There are no perfect tests but current tests for HIV are close.  Infections that are not detected give rise to sensitivity estimates of less than 100%.  Infections may not be detected because of problems with the specimen or the assay being used.  They are rarely due to operator error

2.  Yes, repeat testing with different tests which give the same result (no infection) make the result more reliable.  

3.  Repetitive for question 1.  See reply.

4.  Repetitive for question 2.  See comment above.  The accuracy of your testis is more than 99.5%

This is my final reply to your repetitive, anxiety-driven questions. There will be no more responses and should you return to the site with similar questions regarding test performance and the exposure you described, your question may be deleted without a response and without return of your posting fee,.  EWH