T Watson P, MA, B; S Wattley SOC, PS; H Webster MS; J Webster E*, ME*, EL*, H; S White AD; J Whiteley PY, B, C; T Whiteley TT, TH; L Whitley BUS, SOC, MM; O Whittell P, MA, MS; C Whitwam PY, E/EL, ME*; A Whitworth MM; O Widdop PY*, SOC*, E*; C Wilcock PY, EL; M Wilford PY, ME, EL; I Wilinsky EL, PS, H, MM; B Wilkinson AD, ME.
Prothrombin time (PT) Prothrombin time (PT) is a blood test that measures the time it takes for the liquid portion (plasma) of your blood to clot. A related blood test is partial thromboplastin time (PTT). A blood sample is needed. If you are taking ant blood-thinning medicines, you will be watched for signs of bleeding.
Activated Partial Thromboplastin Time (aPTT) and Prothrombin Time (PT), PT and aPTT, PT and PTT.A. Quick Overview. The prothrombin time (PT) w/INR test measures the length of time it takes for a blood clot to form in a sample of blood. Partial Thromboplastin Time (PTT) test is ordered when someone has unexplained bleeding or clotting.