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.
Prothrombin time (PT) measures the presence and activity of five different blood clotting factors (factors I, II, V, VII, and X). This test measures the integrity of the extrinsic and common pathways of coagulation. The prothrombin time (PT) measures the clotting time from the activation of factor VII through the formation of the fibrin clot.