Requirements for the electronic crossmatch.

With the integration of laboratory information systems into transfusion services, it is now possible to develop standard operating procedures (SOPs) for an electronic crossmatch (EXM) to replace the immediate-spin crossmatch for detecting ABO incompatibility between the blood sample submitted for pre-transfusion testing and the donor unit selected for transfusion. Essential to the safety of an EXM are requirements that: 1) the computer contains logic to prevent assignment and release of ABO incompatible blood; 2) no clinically significant antibodies are detected in the recipient's serum/plasma and there is no record of previous detection of such antibodies; 3) there are concordant results of at least two determinations of the recipient's ABO type on record, one of which is from a current sample; 4) critical elements of the system have been validated on-site; and, 5) there are mechanisms to verify the correct entry of data prior to release of blood. EXM procedures are in use in at least 10 North American facilities, Scandinavia, Hong Kong and Australia. Some provide blood at remote sites lacking laboratory services. Experience has shown that a combination of properly programmed computer software and carefully developed SOPs can provide a safe and efficient means of detecting ABO incompatibility without performing a serological crossmatch.