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Effect of Higher Centrifugation Speed and Shortened Centrifugation Time on Prothrombin and Activated Thromboplastin Time

Technical report

Centrifugation of blood samples to produce platelet-poor plasma is one of the important steps for coagulation testing. Reduction of the time required for specimen processing without affecting quality of results should be ideal for tests which require immediate results. Centrifugation of platelet-poor plasma (3580 rpm) for 15 minutes performed for routine coagulation tests would prolong the turn-around time for an urgent test (30 minutes). This study was done to determine the effect of reducing centrifugation time for routine coagulation tests in order to meet the turn-around time (TAT) for urgent tests. Seventy-nine blood samples sent for routine coagulation tests, were assayed for prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen level and platelet counts, using two different centrifugation speed for plasma preparation: centrifugation at 3580 rpm for 15 minutes and rapid centrifugation at 4000 rpm for five minutes. Paired sample t-test showed that there was a significant difference in the platelet count between the two groups (p=0.001). However, there was no significant difference in the normal APTT (p=0.16), abnormal APTT (p=0.80), abnormal PT (p=0.43) and the results of fibrinogen levels (p=0.36). In conclusion, rapid centrifugation at 4000 rpm for five minutes does not modify results of routine coagulation tests (PT, APTT and fibrinogen). It would be beneficial in providing rapid results for urgent coagulation tests.