Safety in transfusion practice. Is it safe to eliminate the major crossmatch for selected patients?

If a patient has no clinically significant unexpected antibodies, a major crossmatch is not required prior to blood transfusion so long as a test method that demonstrates ABO incompatibility is done. In this study, the safety of using a noncrossmatch method for detecting ABO incompatibility was compared with the use of an immediate spin crossmatch (ISCX). This noncrossmatch method consisted of the duplicate ABO testing of blood recipients, the repeated ABO testing of donor blood, and a clerical check to assure that only ABO matched or compatible blood was selected for transfusion. During the one-year study, 7124 patient samples were tested in duplicate for ABO, 26,942 U of red blood cells received from blood collection facilities were retested for ABO, and 23,962 U of blood selected for transfusion based on the noncrossmatch method were tested by an ISCX. ABO test results were concordant for 7115 of 7124 patient samples and discordant for nine. Seven of the nine discordant patient test results were resolved prior to transfusion, and two were inadvertently overlooked. ABO test results were concordant for 26,922 of 26,942 donor units and discordant for 20. Seventeen of the 20 discordant donor test results were resolved prior to transfusion and three were inadvertently overlooked. Two ABO incompatibilities were missed by the noncrossmatch method but were detected by the ISCX. Unless clerical errors can be totally eliminated, it may be safer to retain the ISCX.