COMPARISON BETWEEN THE CONVENTIONAL TUBE TECHNIQUE AND THE GEL TECHNIQUE IN DIRECT ANTIGLOBULIN TESTS

Objectives: The direct antiglobulin test (DAT) is a diagnostic procedu re demonstrating in-vivo antibody or complement coating on red cells. The gel technique (GT) for this test is sensitive and easier to do tha n the conventional tube technique (CTT). Methods: We tested 52 newborn s with hyperbilirubinemia and 6 children and 17 adults with autoimmune hemolytic anemia (AIHA) using the (DAT) in the form of the convention al tube technique (CTT) and the gel technique (GT) simultaneously. The gradings of the agglutination reactions of both techniques were score d as 12, 10, 8, 5, 3, 0 for 4+, 3+, 2+, 1+ and w+ and negative, respec tively. Results: The GT yielded higher scores than the CTT (p < 0.01). The overall sensitivity and specificity of the GT were 93.5 and 88.6% , respectively. The specificity of the DAT-positive results in newborn s was determined by IgG only, while in AIHA, it was determined by IgG and/or C3d and, in only one sample, by IgM. Conclusion: The GT is equa l to or better than the CTT. Since the GT is simple, the exposure of b lood bank personnel to the blood sample is low. We highly recommend th e GT, especially in areas where HIV infection is prevalent.