Is a room-temperature crossmatch necessary for the detection of ABO errors?

The detection of anti-A and anti-B isohemagglutinins by low-ionic-strength saline tests at 37 degrees C and by the indirect antiglobulin technique, without an "immediate'spin" or room-temperature phase, has been studied. Using such a procedure, all but one of 2746 patient blood samples reacted in accordance with ABO type when tested against A2 and B red cells. However, the discrepant sample also was nonreactive when tested by "immediate-spin" technique against saline-suspended A2 red cells. Our findings indicate that compatibility tests performed at 37 degrees C in low-ionic-strength saline are as sensitive as "immediate-spin" tests with saline-suspended red cells for the detection of ABO errors. Performing serologic tests for unexpected alloantibodies and donor-recipient compatibility without an "immediate-spin" or room-temperature phase abbreviates pretransfusion testing and reduces the detection of clinically insignificant alloantibodies solely reactive at room temperature.