Limitations of the crossmatch for detection of incompatibility between A2B red blood cells and B patient sera.

A recent evaluation of the immediate-spin crossmatch has revealed limitations when used for the detection of ABO incompatibilities in tests between group B patient sera and group A2B donor red blood cells. Presented with the option of deleting the anti-globulin crossmatch, the study reported here was conducted to determine whether the anti-globulin crossmatch would detect the ABO incompatibilities missed by the immediate spin. Results of 1,000 crossmatches between group B patient sera and group A2B red blood cells showed that the anti-globulin phase was capable of detecting a higher percentage of incompatibilities than the immediate-spin procedure, 79.4-86.8% versus 40-64.4%, respectively, depending on the enhancement used. Although anti-globulin testing did detect a substantially higher number of incompatibilities, are the increased cost of reagents and technologists' time used in performing the anti-globulin crossmatch justified for the detection of ABO incompatibilities? Due to limitations observed with the anti-globulin test in addition to budgetary and fiscal constraints, retention of the anti-globulin testing purely for ABO compatibility is not warranted.