Which of the following conditions will most likely result in a false-negative DAT test?

The correct answer is that insufficient washing of red blood cells (RBCs) will most likely result in a false-negative direct antiglobulin test (DAT). The DAT is designed to detect antibodies that are bound to the surface of RBCs. If the RBCs are not adequately washed, residual serum proteins or other substances may remain on the cells, which can interfere with the binding of the anti-human globulin reagent used in the test. This interference could lead to a lower than expected signal or a failure to detect the presence of bound antibodies, ultimately resulting in a false-negative result.

In contrast, the use of heavy chain-specific polyclonal anti-human Ig may not directly impact the sensitivity of the test in the same way. While it could lead to issues in detection depending on the type of antibodies present, it does not inherently lead to the likelihood of false negatives as clearly as inadequate washing does.

Excessive centrifugal force can also lead to false-negative results by causing damage to the RBCs or facilitating the removal of antibody-coated cells from the sample without proper detection. However, these effects are less direct and less common than the issues caused by insufficient washing.

Obtaining a sample by finger puncture might introduce less volume and could potentially be more contaminated