Bleeding and Clotting Time

• HEMOSTASIS


  Ability of the blood and blood vessels to stop bleeding
• 3 PHASES OF HEMOSTASIS

  • Primary Hemostasis
  • Secondary Hemostasis
  • Fibrinolysis
• PRIMARY HEMOSTASIS


  is the initial response of the body to vascular injury, and involves interaction between platelets, adhesive proteins located in the subendothelial matrix (including collagen and von Willebrand factor), and circulating fibrinogen.
• PLATELET PLUG FORMATION


  also known as primary hemostasis, is the first step of hemostasis and is the process where a platelet plug forms to prevent further loss of blood from a damaged vessel.
• What is the end product of Primary Hemostasis?

  Platelet Plug Formation
• VASOCONSTRICTION


  is the narrowing (constriction) of blood vessels by small muscles in their walls. When blood vessels constrict, blood flow is slowed or blocked.
• SECONDARY HEMOSTASIS


  is defined as the formation of fibrin through the coagulation cascade. The coagulation cascade has been classically separated in three pathways: intrinsic, extrinsic, and common pathways.
• In secondary hemostasis, it activates the plasma coagulation

  factors :

  • Fibrinogen
  • Prothrombin
• Once coagulation factors are activated it will produce a solid fibrin clot. The SOLID FIBRIN CLOT stabilizes the platelet plug
• FIBRINOLYSIS


  is the degradation of the fibrin network of a blood clot.
• Bleeding Time


  • Original test for primary hemostasis
  • Measures the time it takes for bleeding to stop from a standardized incision
  • Used to assess platelet and blood vessel integrity
• Method of Bleeding time :

  • Duke Method
  • Ivy Method
• Duke Method of Bleeding Time

  Site of puncture :

  • Palmar surface of middle or ring finger
  • Earlobe
• Normal Range of Bleeding Time

  • Duke Method : 2-9 minutes
  • Prolonged result is suggestive of platelet or vascular disorders
• Clotting Time


  Original test for secondary hemostasis

  • Measures the time it takes for blood to clot in vitro = outside the patient’s body
• Clotting TIme


  Used for screening coagulation protein deficiency / disorders
• METHODS OF CLOTTING TIME DETERMINATION

  • Slide / Drop method
  • Capillary Tube Method
  • WB / Plasma Procedures
• SLIDE / DROP METHOD OF CLOTTING TIME

  Site of Puncture :

  • Palmar surface of middle or ring finger
• Normal Range of Clotting Time :

  • Slide / Drop Method : 4 - 10 mins
  • Prolonged result is suggestive of coagulation factor deficiency or vitamin K deficiency
• Technical factors affecting clotting time:

  1. Presence of anticoagulants
  2. Lower temperature
• Technical factors affecting bleeding time:

  1. Skin thickness at the puncture site
  2. Size and depth of the wound
• Limitation of Duke Method of Bleeding Time

  • Subject to variability
  • Uncommon due to availability of more precise test
• Limitation of Slide/Drop Method of Clotting Time

  • Subjective (Since it is manual, it is subjected to different random error )
  • Less sensitive
  • Not Standardized (May introduce some biases in some results)