Coagulation failure Flashcards
describe 5 clinical features of bleeding disorders
site of bleeding- skin, mucous membrane, joints, muscle
petechiae
bruising
3 main components of a blood clot
fibrin mesh
platelets
RBCs
Lab investigation of bleeding
FBC and film
coagulation tests
platelet-dependent haemostasis
global tests
give 5 coagulation tests
prothrombin time INR APTT thrombin time mixing studies factor assays
3 examples of platelet dependent haemostasis
vwf
platelet function analyser
platelet aggregometry
2 types of global test
thromboelastography
thrombin generation
what does an abnormal PT test result show
F VII deficiency
what does an abnormal APTT test result show
Factor VIII, IX or XI Factor XII (clinically insignificant) Contact factor (clinically insignificant) deficiency
what does an abnormal PT and APTT test result show
Factor II, V or X deficiency
what does an abnormal thrombin time test result show
fibrinogen deficiency
basic principle for clotting tests
incubate plasma with reagents necessary for coagulation
measure time taken to form a fibrin clot
Give 5 examples of an inherited bleeding disorder
Haemophilia A Haemophilia B Von Willebrand disease Factor VII deficiency Haemophilia C Collagen disorders Platelet abnormalities e.g. thrombocytopenia and thromboasthenia
Describe the process of clot formation
• Primary haemostasis:
o Vasoconstriction
o Platelets adhesion within seconds
o Platelets aggregation and contraction within minutes- activated by vwf. The activated platelets provide the surface on which secondary haemostasis takes place
• Secondary haemostasis:
o Activation of coagulation factors within seconds
o Formation of fibrin within minutes
• Fibrinolysis:
o Activation of fibrinolysis within minutes
o Lysis of the plug within hours
