Compatibility testing includes ABO and RH grouping for recipient and/or donor, and screening for unexpected antibodies in patient and donor sera. The cross-match process has become part of a series of pre-transfusion tests known as compatibility testing. The cross-matching procedure determines whether the donor and recipient blood are compatible (or incompatible). Major Cross-match is used to detect antibodies against donor erythrocytes in patient serum. Minor Cross-match is used to detect antibodies against patient (recipient) erythrocytes in donor serum.