[Critical analysis of the routine use of the direct antiglobulin test in 22,517 cross-matching tests].

Routine performance of the direct antiglobulin test (DAT) in pretransfusion testing (PT) is controversial. To evaluate its usefulness, we review the positive DATs found in 22,517 PT performed in our center in the last five years. DAT was positive in 330 PT (1.4%). Eluate studies gave information, not obtained from the rest of PT, in 6 cases. DAT predictive value is low (1.8% of the positive DATs, 0.02% of all PT). Although this predictive value is low, we keep on follow including DAT in PT but we have reduced eluate studies to 1) positive DAT of untransfused patients (to get information of the DAT prior to transfusion and to detected autoimmune haemolytic anaemias) and 2) positive DAT of previously transfused patients with previous negative DAT or changes in its reactivity (for the prompt detection of clinically significant antibodies).