Limitation of the immediate-spin crossmatch

Eighteen months' experience with a manual polybrene crossmatch in a large hospital transfusion laboratory

For 18 months in this laboratory the manual polybrene technique (MP) has been used as the only crossmatching procedure preceded or accompanied by an antibody screen comprising two-stage papain and LISS antiglobulin techniques. There were 17,161 requests representing 43,006 blood units crossmatched and 20,841 units transfused. Non-specific reactivity with the MP required use of an antiglobulin crossmatch in approximately 0.2% of patient samples. Heparin in excess of 20 IU/ml reduced polybrene aggregation of red cells necessitating an antiglobulin crossmatch for 2 patients. Of 288 antibodies detected 20 reacted exclusively by MP compared with 18 by the papain procedure. The data supported the use of MP as an alternative to enzymes in antibody screening protocols. The polybrene technique was found to be a superior abbreviated crossmatch compared with the immediate spin technique and was applicable to all patients including those with known antibodies.

Is the indirect antiglobulin crossmatch justified?

Pretransfusion testing has undergone a rationalization, resulting in a more efficient transfusion service but with no compromise to patient safety. Current debate centres on the necessity of performing an antiglobulin crossmatch if a suitable screening test for detecting red cell antibodies is negative. A retrospective study of all pretransfusion testing was undertaken to determine the specificities and possible clinical significance of antibodies detected by the crossmatch alone. The results indicate that omission of the crossmatch will not compromise patient safety. This will have benefits to both the patient and the laboratory. The patient will benefit because of less time needed to provide homologous donor blood. The laboratory will benefit from cost savings as a result of less antiglobulin reagent being used, less time taken for providing blood (and hence further cost savings) and less blood needing to be held in stock. The cost savings generated could be channelled into areas that will result in greater patient safety at a lower cost than crossmatching. Two of these areas are prevention of patient and specimen identification errors by the use of a unique transfusion number system and the full utilization of an autologous blood service.