ABSTRACT
A variety of pretransfusion tests have been developed to improve the safety and effectiveness of transfusion. Recently, a number of traditional tests have been shown to offer limited clinical benefit and have been eliminated in many facilities. A survey of pretransfusion test practices was distributed to 116 hospital transfusion services. Routine test practices and facility size were analyzed. Ninety-one responses were received. Many smaller laboratories include tests such as anti-A,B, an autocontrol, and DAT, and immediate spin and 37 degrees Celsius microscopic readings. Nine percent never perform an Rh control with anti-D typing on patient samples. Various antibody screening and crossmatch methods are utilized. Individual laboratory test practices should be periodically assessed to ensure that they comply with standards, represent the recognized best practice, and are cost-effective. The survey responses indicate that many laboratories perform tests that are not necessary or cost-effective. These facilities should review their processes to determine which tests contribute to transfusion safety. Smaller facilities may be reluctant to change or lack the expertise necessary for this decision making and often continue to perform tests that have been eliminated in larger facilities. Consultation with larger hospital transfusion services may provide guidance for this change.
ABSTRACT
The most likely cause of fatality in blood transfusion is transfusion of the wrong unit of blood to a patient. This type of error is usually attributed to improper patient identification at the time of sample collection or transfusion. A retrospective analysis of the results of an external proficiency testing program identified a common source of error occurring during laboratory testing that has not been previously reported. Results were analyzed when major errors were assigned to laboratories for obviously switching donor units in compatibility testing and/or subsequent investigation. In 24 surveys sent to extended testing (Level A) laboratories and 18 sent to basic testing (Level B) laboratories, the antigenic composition of the two donor cells made it possible to determine whether the cells had been switched. Seven errors were assigned to Level A participants for switching donor units during testing, constituting 38.9 percent of the 18 major errors assessed. Level B participants were assigned eight errors for switching donor units, 26.7 percent of the 30 major errors assessed. Approximately one-third (31.3 percent) of major errors committed on 42 proficiency testing surveys were caused by switching of donor cells during compatibility testing. This type of error may result in transfusion of an incompatible donor unit.
ABSTRACT
Instructions included with monoclonal Rh(D) typing reagents do not require routine use of an Rh control as immunoglobulin-coated red blood cells (RBCs) rarely yield falsely positive results with low protein reagents. However, the American Association of Blood Banks (AABB) Technical Manual recommends a concurrent control be performed on patients' RBCs that type as group AB, D(+). Proficiency testing surveys presented sensitized AB, D- RBCs, which resulted in a positive direct antiglobulin test and, in some samples, spontaneous agglutination in saline. One intent of the surveys was to monitor the accuracy of the reported Rh(D) type. On an initial survey, 19 of 115 (16.5%) participants reported the RBCs as D(+). Of these laboratories, 63.2 percent (12/19) had used a monoclonal/ polyclonal blend anti-D reagent. On a subsequent survey, after educational material had been distributed, only five of 113 (4.4%) participants reported the Rh type as D(+). Two of these five laboratories had used a monoclonal/polyclonal blend anti-D reagent. As RBCs coated with immunoglobulin may give unreliable results with Rh typing reagents, laboratories should follow the guidelines of the AABB Technical Manual. An appropriate control should be performed whenever RBCs from patients type as AB, D(+).
ABSTRACT
Sera from 29 patients who had reacted to a platelet (27) or packed red cell (2) transfusion and from 5 patients who had received platelets without reacting were collected over a 13-month period. The sera were assayed for total IgE, and IgE specific for ethylene oxide, phthalic anhydride, hexamethylene diisocyanate, methylene diphenyl diisocyanate, toluene diisocyanate, and mast cell tryptase. Three patients with reactions had elevated total IgE levels, and specific IgE was positive for hexamethylene diisocyanate in 2 of 28 (7.1%), methylene diphenyl diisocyanate in 1 of 29 (3.4%), and toluene diisocyanate in 14 of 27 (51.9%). No positives were found in patients without reactions and no patients had an elevated tryptase level. It is unlikely that anti-plasticizer hypersensitivity was responsible for the transfusion reactions, but the prevalence and significance of such antibodies in both the hospital population and the general population would merit further investigation.
