Evaluation of polyethylene terephthalate for ABO and Rh typing and alloantibody screening

BACKGROUND: For many years, hospitals and laboratories have used evacuated glass tubes for blood collection. To improve the safety of blood collection , plastic polyethylene terephthalate (PET) tubes (Vacutainer PLUS, Becton D ickinson) have been developed. The objectives of this study were to compare the accuracy of ABO grouping, Ph typing, and antibody screening of blood s amples collected in plastic tubes with that in glass tubes and to determine if refrigerated blood samples collected in plastic tubes remained stable o ver a 28-day period. STUDY DESIGN AND METHODS: Samples were collected from 121 volunteers, at le ast 30 from each of the A, B, 0, and AB blood groups, in four types of Vacu tainer tubes: silica-coated plastic, K-2, EDTA plastic, uncoated glass, and K-2, EDTA glass. Samples from each tube were tested for ABO group and Rh t ype by use of the microtyping gel identification card system and the tube m ethod. A three-cell antibody screen was performed by the microtyping gel ca rd technique with a monospecific IgG reagent. Initial samples were tested w ithin 3 hours of collection. Refrigerated samples were retested for ABO and Ph type and antibody screening 1, 2, 21, and 28 days later. Agreement betw een test results was determined by using Cohen's Kappa statistic. RESULTS: Complete agreement was observed between the ABO and Rh typing resu lts in samples drawn into glass and plastic tubes of both the EDTA and nona nticoagulated type (kappa = 1.0). In retesting, there were no examples of a change in ABO or Ph type over the 28-day study period. Only two alloantibo dies (1.7%) were identified in the 121 samples, and no difference was obser ved in alloantibody expression in either plastic or glass Vacutainer tubes over the 28-day study period. CONCLUSION: Samples collected into the PET serum or EDTA tubes provided acc urate ABO and Ph typing results that remained consistent over a 28-day peri od. Samples collected in these tubes also appeared to enable accurate alloa ntibody identification. However, the number of alloantibodies identified in this study was small, and this result should be confirmed in a larger seri es.