[Changes in the structure and clinical significance of the positive results of pretransfusion testing during the switching from tube test agglutination to gel microcolumn technique].

AIM To investigate the changes in pretransfusion testing during the switch from the agglutination tube test to the gel test. METHODS Clinical significance of positive results has been analyzed in 7667 pretransfusion tests (with 16610 cross-matches) performed by the tube test in 2005-2006, and in 7372 pretransfusion tests (with 17294 cross-matches) performed in 2007-2008 by the gel test. RESULTS In both analyzed periods antibody detection was positive in 1.3% and cross-matching in 0.3% cases. At least one test was positive in 1.4% pretransfusions tested by the tube test and in 1.3% by the gel test, with >75% positive results in women. Analyzing cases with positive cross-matching but negative antibody detection, eight of ten such cases found by the tube test were caused by 'cold antibodies' whereas 'warm non-specific antibodies' caused all three cases found by the gel test. The gel test detected higher proportion of immune antibodies than the tube test (69.8% vs 41.3%, p < 0.001), with a double increase in anti-K and Rh antibodies. The tube test detected 24 cases of clinically non-significant antibodies, as compared with no cases found by the gel test (p < 0,001). 'Non-specific antibodies' more often caused positive cross-matches than antibody detection (42.6% vs. 29.9% by the tube test, 28.9% vs. 18.3% by the gel test). Despite of being close in the detection of irregular antibodies (p=0.062), the difference between the tube and gel test was not significant. 'Non-specific antibodies' were found by both tests more often in women, while clinical departments were of no significance. CONCLUSIONS The gel test has proved to be a more optimal technique of pretransfusion testing. The detection of irregular antibodies is recommended as an obligatory part of pretransfusion testing.