2005 Volume 51 Issue 6 Pages 565-570
The automated blood group testing system based on column agglutination technology (CAT) does not provide a standard for reversed typing. If the tube test (TT) method standard is introduced into automated the CAT method, the frequency of confirmation testing with the TT method will increase. In this study, we compared the results of the CAT and TT methods using samples which produced weak results with the automated CAT method (reactivity<3+; AutoVue System, Ortho).
Forty-five percent of weak samples showed an increase in agglutination reactivity after a fixed 3-minute incubation time with the manual CAT method (Bio Vue, Ortho). All 481 weak samples had greater than 3+ reactivity with the TT method. Eighty percent of weak samples possessed IgM antibody. Titration and scoring results with the TT method were greater than with the manual CAT method for all samples. Titration and scoring of the weak samples were low with all methods for all samples. In conclusion, we propose that 1+ reactivity in the automated CAT method requires a confirmation test with the TT method because CAT 2+ samples can present as 3+ with the TT method.
