مقایسه زمان پروترومبین در نمونه های خون وریدی لوله اول و دوم

Background and purpose : In The current practice to measure prothrombin time(P.T.). the second tube of venous blood is used for testing. This practice derived from early experience using first tube of venous blood and non-disposable needles which inevitably resulting to release of tissue thromboplastin from traumatized blood vessel wall, and so the estimated time was falsely shortened. Using modern phlebotomy methods by inexperienced phlebotomists were resulted in unfavorable outcome, too. According to a new research , using evacuated tubes by experienced phlebotomists yields accurate results by the first tube. This study designed ti use other standard phlebotomy instruments and to compare P.T. of the first and second tubes within two groups of patients those used and those not used warfarin. Materials and Methods : paired blood specimens were collected from two equal groups of patients a groups of fifty patients (Group A) were taking warfarin and another equal group (Group B) were not. Tests were performed on the first and second tubes. Results : In Group A mean P.T. of the first and second tubes were 18.93 sec and 19.26 sec , respectively. In Group B mean P.T. of the first tubes was 12.78 sec and that of the second tubes was 13 sec. Conclusion : Tte different between P.T. of the first and second tubes was not statistically sinnificant. Therefore , by performing P.T. test on specimens collected by experienced phlebotomists, the first tubes yield accurate results