Critical evaluation of donor direct antiglobulin test positivity: Implications in cross-matching and lessons learnt

Direct Antiglobulin Test is a method of demonstrating the presence of antibody/ complement bound to red cell membrane by using AHG to form a visible agglutination reaction. DAT positivity is seen in immune mediated haemolytic anaemias, however rarely non immune mediate haemolytic anaemias also show DAT positivity. DAT positivity predictive of 83% of autoimmune haemolytic anaemia and 1.4% cases without haemolytic anaemia. Screening of blood donors for DAT is usually not recommended traditionally by any guidelines. However DAT positivity is reported in 0.008% of donors. On extensive search of literature we could find only very few studies on DAT positivity in donors. We report two cases of DAT positive donors with no clinical or laboratory evidence of hemolysis.