Coagulation studies are performed to evaluate the components and pathways of the coagulation sequence. Innumerable tests have been devised to diagnose inherited, acquired, and iatrogenic deficiencies of coagulation. Some of these require specialized techniques or rare reagents available only in laboratories that perform many such tests. Other tests are less precisely diagnostic but more available and more readily applicable to immediate clinical situations. The tests included here are widely available.
Screening tests of hemostatic function include the platelet count, bleeding time, prothrombin time, and partial thromboplastin time. When a "coagulation profile" or "coagulogram" is ordered, it includes the four screening tests plus clotting time and activated partial thromboplastin time.