Test for extrinsic and common coagulation pathway is ?
PT
aPTT
Bleeding time
Thrombin time
Ans. is 'a' i.e., PTPatients with hemophilia have deficiency of factor VIII that results in prolonged PTT.Tests used to evaluate different aspects of hemostasis.i) Bleeding timeIt is not a test for coagulation rathers it tests the ability of the vessels to vasoconstrict and the platelets to form a hemostatic plug.It is the time taken for a standardized skin puncture to stop bleeding.Normal reference value is between 2-9 minutes.Prolongation generally indicates the defect in platelet number or function.ii) Prothrombin time (PT)This assay tests the extrinsic and common coagulation pathway.So, a Prolonged PT can result from deficiency of factor V, VII, X, prothrombin or fibrinogen.