What is an indeterminate Western blot result?
The Western blot test is used as a confirmatory test in the US and some other countries. This test can separately detect antibodies to various HIV proteins. If several types of antibodies are detected then the result is positive; if no antibodies are detected then the result is negative. If the test appears to show only one or two types of antibodies then the result is called indeterminate, or inconclusive. There are two main reasons why this can happen. Firstly, it may be that the person has only recently become infected with HIV, and has not developed a full immune response. Secondly, the test may be showing a weak reaction to other antibodies unrelated to HIV. An indeterminate result indicates that further testing is required. Either the Western blot may be repeated a few weeks later, or a different test (such as PCR) may be used.
