Blood collection tubes made from plastic are beginning to replace glass tubes. Coagulation test results can be influenced easily by preanalytic factors, including exposure to surfaces that activate the clotting cascade.
To compare the effects of the blood collection tube material on 22 coagulation assays performed in clinical laboratories.
Paired blood samples from 28 healthy volunteers were drawn into BD Vacutainer Glass Citrate Tubes and BD Vacutainer Plus Plastic Citrate Tubes, and the results of coagulation assays were determined in parallel.
No statistically significant differences were observed between glass and plastic for 14 assays: prothrombin time (and international normalized ratio); activated partial thromboplastin time; activated protein C resistance; antithrombin activity; factors II, V, VIII, and IX; alpha2-antiplasmin; plasminogen activity; von Willebrand factor antigen; ristocetin cofactor; thrombin time; and reptilase time. Statistically significant differences were found for fibrinogen; chromogenic protein C activity; protein S activity; PTT-LA lupus anticoagulant-sensitive activated partial thromboplastin time; and factors VII, X, XI, and XII. Mean differences ranged from 0.4% to 5.5% and were unlikely to be of clinical significance.
The results of this study suggest that plastic tubes can be used in place of glass tubes for a wide variety of coagulation assays.