Critical elements of the information system have been validated on-site.
Using AABB guidelines, the electronic crossmatch is possible only if the following conditions are met:
Critical elements of the information system have been validated on-site.
No clinically significant antibodies are detected in the current blood spample and there is no record of clinically significant anibodies in the past.
The patient's ABO group and Rh type has been done twice
and entered in the computer (one group can consist of a
record but one must be done on a current in-date specimen). The two groups must agree.
The donor ABO (and Rh types, if negative) have been
confirmed and entered in the computer. The donor unit identification number, component name, and ABO/Rh type must also be entered in the computer (e.g., by scanning the bar code label on the unit). The two groups must agree.
A method exists to verify correct data entry and interpretation prior to release of blood, e.g., a screen that requires the technologist to input yes/no or accept/do not accept before the ABO results and their interpretation are accepted; computer logic that will reject incorrect ABO interpretations of recorded results.
The computer system will alert the technologist
to ABO & Rh discrepancies between information on the donor label and results of donor confirmatory
testing.
The computer system will alert the technologist
to ABO and Rh discrepancies patient and donor groups. The program should be programed to prevent assigning ABO incompatible blood (e.g., group A red cells to a group O recipient) and to give an alert when assigning Rh-positive red cells to Rh-negative recipients.
Note that an electronic crossmatch is nothing more than using a computer to assign a unit of blood to a patient. The sole purpose of the electronic crossmatch is to confirm ABO compatibility between patient and donor. It cannot prevent hemolytic transfusion reactions caused by patient antibodies that are missed by the antibody screen; it cannot prevent hemolytic reactions due to patient misidentification errors.
Note: Most transfusion services do not yet use the electronic crossmatch for several posible reasons: lack of an LIS with suitable blood bank software; reluctance to give up a serologic crossmatch, even an immediate-spin crossmatch; in the USA, unwillingness to do the work required to meet AABB and FDA requirements and to do the on-site validation required by the FDA.
Computer-assisted crossmatches must not be done for patients with:
a record of clinically significant
antibodies (even if they are now undetectable)
currently detectable clinically significant antibodies
unresolved ABO discrepancies
Below is the Medline abstract for a paper on the computer-assisted crossmatch. For a fuller discussion, also see this paper : Butch SH, et al. The computer or electronic crossmatch. Transfus Med Rev 1997; 11(4): 256-64.
BACKGROUND: This article describes standard operating procedures (SOPs) for a computer crossmatch to replace the immediate-spin crossmatch for ABO incompatibility between patient blood samples submitted for pretransfusion testing and the blood component selected for transfusion. These SOPs were developed following recent changes to the Standards for Blood Banks and Transfusion Services of the American Association of Blood Banks (AABB).
STUDY DESIGN AND METHODS: SOPs were developed, utilizing currently available software, for pretransfusion testing. The SOP for donor unit processing entails bar code entry of the unit number, component name, and ABO/Rh type; computer entry and interpretation of serologic reactions; warning of discrepancies between bar code-entered blood type and result interpretation; and quarantine of the donor unit in such instances. The SOP for patient sample testing requires bar code entry of specimen accession number, which accesses patient demographics; computer entry and interpretation of ABO/Rh tests; repeat blood typing at the time of crossmatch if only one patient blood type is on record; and warning if there are nonconcordant current and historical blood types. The computer crossmatch SOP requires bar code entry of specimen accession and donor unit numbers; release of group O red cells pending resolution of discrepancies; and immediate-spin crossmatch during computer downtime. Tables validated on-site prompt warning messages and prevent both computer crossmatch and release if blood components of the wrong ABO type are selected.
RESULTS: These SOPs meet the requirements of the 15th edition of the AABB Standards. Projected annual time savings at this institution are > 100,000 workload recording units. Further benefits include reduced patient sample volume requirements, less handling of biohazardous material, and elimination of unwanted positive or negative reactions associated with the immediate-spin crossmatch. Release of incompatible blood components when the wrong patient blood type is on record is addressed by requiring the use of group O red cells in the absence of two concordant blood types, one of which must be from a current sample.
CONCLUSION: A combination of existing computer programs and carefully developed SOPs can provide a safe and efficient means of detecting donor-recipient incompatibility without performance of serologic crossmatch.
 MSBOS
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