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 Dickinson) have been developed. The objectives of this study were to compare the accuracy of ABO grouping, Rh typing, and antibody screening of blood samples collected in plastic tubes with that in glass tubes and to determine if refrigerated blood samples collected in plastic tubes remained stable over a 28-day period.
Study design and methods: Samples were collected from 121 volunteers, at least 30 from each of the A, B, O, and AB blood groups, in four types of Vacutainer 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 type by use of the microtyping gel identification card system and the tube method. A three-cell antibody screen was performed by the microtyping gel card technique with a monospecific IgG reagent. Initial samples were tested within 3 hours of collection. Refrigerated samples were retested for ABO and Rh type and antibody screening 1, 2, 21, and 28 days later. Agreement between test results was determined by using Cohen's Kappa statistic.
Results: Complete agreement was observed between the ABO and Rh typing results in samples drawn into glass and plastic tubes of both the EDTA and nonanticoagulated type (kappa = 1.0). In retesting, there were no examples of a change in ABO or Rh type over the 28-day study period. Only two alloantibodies (1.7%) were identified in the 121 samples, and no difference was observed 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 accurate ABO and Rh typing results that remained consistent over a 28-day period. Samples collected in these tubes also appeared to enable accurate alloantibody identification. However, the number of alloantibodies identified in this study was small, and this result should be confirmed in a larger series.