Comparison of Prothrombin Time and Activated Partial Thromboplastin Time in Primary Tubes and Sample Aliquots After 4 Hours Duration

Abstract

Background: Coagulation tests are widely applied in clinical practice, among which PT and aPTT are the most commonly done. Among many preanalytical conditions –time, temperature and storage conditions are few of the factors affecting the results of samples. This study aims to compare PT and aPTT values in primary tubes and sample aliquots after 4 hours duration with the initial value. Materials & Methods : An observational study was done at Central Diagnostic Laboratory, Gandhi Hospital, Secunderabad, T.S. Samples were collected in citrated tubes, centrifuged, PT and aPTT were processed with plasma of primary tubes. Sufcient quantity of plasma was aliquoted immediately from primary tubes and kept at room temperature for 4 hours after which the plasma of primary tubes and aliquots were re-analyzed separately and values were compared. Results: Pearson correlation was performed to show the relation. PT and aPTT values obtained in the primary tube and aliquot were correlating with the initial value (PT-r =0.833,0.831 respectively) and (aPTT-r =0.97,0.87 respectively) and also with each other (PT-r =0.99) and (aPTT-r =0.90) respectively. There is no statistical signicant difference in PT of primary tube and aliquots when compared to initial PT (p>0.01). Incase of APTT there is statistically signicant difference in primary tube and aliquot when compared to initial value (p<0.01) where as there is no signicant difference of APTT values in aliquot and primary tube after 4 hours (p>0.01). Conclusion: The present study shows no difference of PT values in aliquots and primary tube when compared to initial value, whereas APTT values differ from initial values in samples stored for more than 4 hours in primary tube and aliquot.