False reactive HIV rapid antibody test in pregnancy

Abstract

Background: Universal screening of HIV infection in pregnant women is recommended by CDC as well as Indonesia Ministry of Health to prevent mother-to-child HIV transmission. Algorithm of HIV testing in pregnant women in Indonesia is similar to that in Integrated Counseling and Testing Centre (ICTC) which refes to WHO HIV Testing Strategy III. Pregnancy has been observed to be associated with false positive HIV testing that can cause serious emotional distress and unnecessary follow-up. Case Description: A 21 y old pregnant woman was referred to a tertiary hospital with premature rupture of the membranes. Before C-section, preoperative laboratory test panels were ordered, including for HIV to which she consented. A rapid HIV test (A1) was performed and tested reactive for antibodies against HIV. The second (A2) and third (A3) rapid tests were then performed and yielded non-reactive results, concluding the final result as negative. Reassessment of the patients showed no risk factors for HIV infection. This was the third case of reactive A1 with non-reactive A2 and A3 within the last year in the hospital. After confirmatory tests, which came back non-reactive and negative for fourth-generation HIV test and Western Blot, respectively, the A1 test was considered as false positive. Discussion: Based on several reports, there are alloantibodies in pregnancy, transfusions, transplantations, and autoimmune diseases that account for the increased false positive rate. Positive HIV antibody test results can occur in the absence of infection due to cross-reactivity between viral proteins and tested specimens, but such cross-reactivity is less common using current peptide-based EIAs which contain fewer antigens than previous viral lysate-based EIAs. However, clinicians should be aware that when HIV prevalence is low, as is often the case among pregnant women, a reactive EIA result is more likely to be false positive. Conclusion: Counselling and HIV test should be integrated in antenatal care. Diagnostic procedure of HIV test in pregnant women refers to WHO Testing Strategy III. Because the positive predictive value of HIV test in obstetric population is low, positive screening results should be handled carefully and appropriate confirmatory testing should always be pursued.