False positive dat results are most often associated with: a. use of refrigerated clotted blood samples in which complement components coat rbcs in vitrob. a recipient of a recent transfusion manifesting an immune response to recently transfused rbcsc. presence of heterophile antibodies from administration of globulind. a positive autocontrol caused by polyagglutination

a. use of refrigerated clotted blood samples in which complement components coat RBCs in vitro

Explanation:

DAT is direct antiglobulin test. It is also called as Coombs test. It is primarily used for determining the cause of hemolytic anemia. This test looks for the attachment of the antibodies that break apart the red blood cells causing hemolysis.

A false positive DAT result signifies that the eluted antibody cannot bind to the red blood cells. But binding do occur in true positive test.

Thus the result may reflect that it has been conducted on the refrigerated and clotted blood samples yielding a false result in inappropriate results.