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The rapid plasma reagin test (RPR test or RPR titer) is a type of rapid diagnostic test that looks for non-specific antibodies in the blood of the patient that may indicate an infection by syphilis or related non-venereal treponematoses. It is one of several nontreponemal tests for syphilis (along with the Wassermann test and the VDRL test).
Serological assays may give a false positive result, causing the individual to appear to have seroconverted when the individual has not. False positives can occur due to the test reacting to, or detecting, an antibody that happens to be sufficiently similar in structure to the target antibody.
Replacement tests such as the VDRL test and the RPR test, initially based on flocculation techniques (Hinton), have been shown to produce far fewer false positive results. [ citation needed ] Indeed, the "biologic false positives" of modern tests usually indicate a serious alternate condition, often an autoimmune disease .
The false positive rate (FPR) is the proportion of all negatives that still yield positive test outcomes, i.e., the conditional probability of a positive test result given an event that was not present. The false positive rate is equal to the significance level. The specificity of the test is equal to 1 minus the false positive rate.
With nontreponemal tests, false-positive reactions can occur for a large number of reasons, the most common of which is other infections, both viral and bacterial. Additionally these tests may show false-negative when the patient's antibody titer is very high due to a hook effect (also called a prozone effect).
This test tells whether there are antibodies in the maternal plasma. If positive, the antibody is identified and given a titer. Titers of 1:4 or higher is considered critical for Kell (compared to 1:16 for most other antibodies) and is considered to confer a high risk of fetal anemia. [17]
False positive COVID-19 tests—when your result is positive, but you aren’t actually infected with the SARS-CoV-2 virus—are a real, if unlikely, possibility, especially if you don’t perform ...
The false positive rate is calculated as the ratio between the number of negative events wrongly categorized as positive (false positives) and the total number of actual negative events (regardless of classification). The false positive rate (or "false alarm rate") usually refers to the expectancy of the false positive ratio.