How Accurate Is 12 Day RNA PCR Test For HIV Detection?

Posted on Wed, 22 Jan 2014

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

Wed, 22 Jan 2014 Answered on

Tue, 11 Feb 2014 Last reviewed on

Question : Hi, I had protected sex on 25/12/2013. But during intercourse (which lasted for only 30 seconds or less) i lost erection and withdrawned my penis, but then i realised that condom was slipped during those 30 seconds. On 12th day after the incident I did HIV Duo including p24 antigen (4th Gen) and HIV-1 RNA Qualitative by Real Time PCR. The Duo test result came back negative the very same day. And RNA PCR came back as Not Detected after 4 days. The doctor told the detection limit was 20 copies/ml and is very accurate. The details of that test are given below. My Query is "Can i consider my 12 day RNA PCR test as conclusive. And how much % accurate it is at 12th day" HIV-1 RNA Qualitative by Real Time PCR - Not Detected Clinical Background: The qualitative HIV RNA tests use a process called reverse transcription polymerase chain reaction (RT-PCR). This type of qualitative test reports whether HIV is present in the bloodstream or not. The result is reported as either "detected" or "not detected.” If a qualitative RNA test is positive (detected), then it is confirmed that the patient if infected with HIV. The "qualitative" test is more accurate than the "quantitative" test because qualitative tests are able to detect very low levels of the virus. If a patient has a quantitative test that shows no detectable virus, but has a positive result with the qualitative test, it means there is a very low level of virus that can be detected only with the qualitative test. Note: * This test is performed in CAP/ISO 15189:2007 accredited collaborating laboratory.

Answered by Dr. Sankaranantham Murugan (9 hours later)

Brief Answer: 4th generation DUO and RNA PCR are highly reliable Detailed Answer: Hi, Welcome to XXXXXXX Slip of condom after the intercourse did not increase the risk for HIV. So it can be considered as a protective exposure only. So you need not worry. With regard to your test results, HIV antigen would appear as early as a week after the infection (if any), so the 4th generation HIV duo test done after 12 days after the high risk contact came negative is highly reliable. Regarding qualitative RNA PCR confirmed this result as it could not detect any HIV antigen on the 12th day. Both the negative test confirmed that you free fro HIV. Just forget the incident and enjoy the days coming ahead. Dr S.Murugan

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Sankaranantham Murugan (14 hours later)

Dear Doctor, Many websites are giving totally different window periods for different tests. Some say only by 28th day the 4th Gen Duo test will be conclusive and some say by 6 weeks. Same is the case of RNA PCR test also. Some say 16 days, some say 7 days...Please calrify..Doctor, please note that during the incident my penis was inside her uncovered for few seconds. So can i consider my results on 12th day as conclusive.

Answered by Dr. Sankaranantham Murugan (1 hour later)

Brief Answer: Window period for antibody test 3 months.HIV free Detailed Answer: Hi, Welcome to XXXXXXX Window period for any Antibody tests like Rapid, spot tests or ELISA or Western blot tests is around 8-12 weeks. Antigen detecting tests are very sensitive and specific. Antigens are otherwise viral proteins appearing in the circulation as early as 1 week in presence of an infection. In some cases the establishment of the infection and the appearance of the viral proteins in the blood may be delayed or found low in titre. So some experts feel that an antigen test done after 4 weeks is more conclusive one. But as you had both 4th generation DUO test (combination of antigen and antibody Test) and Qualitative HIV RNA PCR test on 12th day you can take it as a conclusive one. If you want, you can repeat the 4th generation DUO after completion of 28 days for your satisfaction to rely the results more conclusive and confidently. You are unlikely to be infected with HIV. Dr S.Murugan

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar