CROSS MATCHING

 CROSS MATCHING PROCEDURE

Types, Purpose, Principle, Procedure and Interpretation

Cross Matching is a procedure performed prior to a blood transfusion to determine whether donor blood is compatible (or incompatible) with recipient blood.

Compatibility is determined through matching of different blood group systems, the most important of which are the ABO and Rh system, and/or by directly testing for the presence of antibodies against a sample of donor tissues or blood.

Purpose of Cross Matching

The crossmatch is routinely used as the final step of pretransfusion compatibility testing. The purposes of compatibility testing are to detect: irregular antibodies; errors in ABO grouping, and clerical errors in patient identification and result recording.

The crossmatch will detect the following:

1. Most recipient antibodies directed against antigens on the donor red blood cells.

2. Major errors in ABO grouping, labeling, and identification of donors and recipients.

Principle

Cross-matching will detect incompatibilities between the donor and recipient that will not be evident on blood typing. There are two types of cross-matches: Major cross-match and Minor cross-match.

The major crossmatch involves testing the patient’s serum with donor cells to determine whether the patient has an antibody which may cause a hemolytic transfusion reaction or decreased cell survival of donor cells. This is the most important cross-match.