[Evaluation of the direct antiglobulin test]

The validity of a direct antiglobulin test (DAT) was evaluated by testing 7645 blood samples from hospitalized patients. DAT was routinely done in 7201 blood samples sent for pretransfusion testing and 444 blood samples specifically sent for the examination of immune hemolysis. Positive DAT was discovered in 0.04% (3/7201) pretransfusion samples and in 3.83% (17/444) samples examined for immune hemolysis. In 16 of the samples with positive DAT, IgG antibodies with or without complements and in 4 samples only components of complements were detected on RBC. The cost of positive DAT in pretransfusion testing is 92 times higher than that of DAT during laboratory investigation of immune hemolysis. Due to a low frequency of positive DAT during pretransfusion testing, its cast and the fact that patients had no clinical signs of immune hemolysis, we advocate no use of a routine DAT during pretransfusion testing.