Why was prewarm LISS used to crossmatch donor units with the post reaction specimen?

Experience with Polyethylene Glycol (PEG) has shown that PEG enhances hemagglutination reactions, especially when autoantibodies are present. The next best thing in this facility is the LISS enhanced crossmatch Because the DAT showed positive reaction with anti-C3, the prewarm was used to avoid cold reactions from interfering (and probably chosen to avoid repeats if very little plasma is left after this extensive investigation).