A medical technologist in Singapore reports that they recently crossmatched an E-positive RBC unit for a patient with anti-E and mistakenly thought that the E-positive RBC unit was compatible and acceptable for transfusion. Apparently, when a technologist crossmatched two RBC units for the patient in question, one of the RBC units was reactive in an antiglobulin crossmatch and the other was non-reactive. The non-reactive RBC unit was typed by the technologists as 'E-negative' and was set aside to be available for transfusion. When a second technologist crossmatched additional RBC units for the same patient, including (for reasons not clear) the RBC unit that had earlier been found to be incompatible, repeat crossmatching showed the 'incompatible' RBC unit to actually be 'compatible' and E-negative. An investigation revealed that the first technologist erroneously typed an E-positive RBC unit as E-negative and erroneously reported the crossmatch result as compatible when in fact it should have been reported as incompatible. Fortunately, the error was discovered before the E-positive RBC unit was transfused to the patient. The inquiring colleague asks for suggestions on how to prevent this kind of error from happening again.

The following comments have been received.

ADDENDA Mar. 19, 2007

1. In the opinion of a blood bank supervisor at a 300+ bed hospital in Central Ohio, the error/event under discussion was technical in nature. He concludes that a donor unit was mistyped as negative for the E antigen when, in fact, that unit was later found to be positive for the E antigen. As a proactive approach, technologists who work under his supervision are required to reconfirm all negative reactions when antigen typing units for the offending antibodies, by preparing a new cell suspension from a different segment that has been taken from the red cell unit under review. This approach permits the technologist to re-identify the units and to provide a check system for catching technical errors such as switching or mixing segments or test tubes during cell suspension preparation. By practicing this approach, he feels that his staff have improved transfusion safety for their patients who have unexpected antibodies.

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