SAINT MARY’S UNIVERSITY
BAYOMBONG, NUEVA VIZCAYA 3700
SCHOOL OF HEALTH AND NATURAL SCIENCES
MEDICAL LABORATORY SCIENCES DEPARTMENT
HEMOSTASIS
Hemostasis
• Stoppage of blood flow
• Involves the interaction of blood vessels, platelets, coagulation mechanism, fibrinolysis, and tissue repair
• Complex process
Cellular Elements of Hemostasis
• Extravascular tissue factor (TF)
• Vascular intima
• Intravascular component
Stages of Hemostasis
• Primary Hemostasis
o Refers to the roles of blood vessels and platelets in the primary formation of platelet plug in
response to vascular injury
o Involves:
▪ Platelet adhesion
▪ Platelet activation
▪ Platelet secretion
▪ Platelet aggregation
o
TEST: BLEEDING TIME
▪ In vivo measure of primary hemostasis
▪ Determines both congenital and acquired platelet disorder
▪ Factors affecting bleeding time:
• Elasticity of the cut tissue
• Ability of the blood vessel to constrict and retract
• Mechanical and chemical action of platelets in the formation of hemostatic plug
▪ Methods:
• Duke’s method
• Ivy’s method: best method to assess platelet’s adhesiveness
• Coply Lalitch method
• Adelson-Crosby method
• Macfarlane’s method
▪ Abnormal bleeding time:
• Thrombocytopenia
• Hypofibrinogenemia
1 | HEMATOLOGY 2 LABORATORY
SAINT MARY’S UNIVERSITY
BAYOMBONG, NUEVA VIZCAYA 3700
SCHOOL OF HEALTH AND NATURAL SCIENCES
MEDICAL LABORATORY SCIENCES DEPARTMENT
•
•
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vWF disorder
Connective tissue disorders
Secondary Hemostasis
o Involves the enzymatic activation of series of plasma proteins in the coagulation system to form
a fibrin meshwork
o
TEST: CLOTTING TIME OR COAGULATION TIME
▪ Measure of the ability of the blood to clot
▪ Not influenced by the platelet functions other than platelet factor 3 (PF 3)
▪ Measures only the time required for the formation of the traces of thrombin sufficient to
produce a visible clot
▪ Methods:
• Capillary blood method
o Slide and drop
o Capillary tube or Dale and Laidlaw’s
• Whole blood/Lee and White method (Tilt tube method)
PREPARED BY:
Desiree Joy B. Arquero, RMT
Instructor
2 | HEMATOLOGY 2 LABORATORY