Electronic crossmatching.

The crossmatch (XM) is an important part of routine pretransfusion testing. It is used to detect ABO incompatibility and other clinically significant antibodies. The XM has been modified many times and, in recent years, has been abbreviated. The 2 common types of XM currently being done are the immediate spin XM for antibody-negative patients and the antiglobulin XM for the rest. The antiglobulin phase of the XM is generally considered optional, unless a clinically significant antibody is present. Originally, the XM was intended to be a final check for ABO compatibility and for the detection of unexpected antibodies. Electronic crossmatching was first introduced at the University of Michigan Medical Center in 1992. This paper summarizes the basic principles, current guidelines, regulatory requirements, and some recommendations that may prove useful for the implementation of electronic crossmatching.