BLEEDING DISORDERS AND THROMBOSIS Flashcards
In a patient with a bleeding disorder where the mucous membranes are most affected, what is the likely underlying pathology?
Platelet defects
Von Willebrand disease
In a patient with a bleeding disorder where the bleeding happens into joint and muscles, what is the likely underlying pathology?
Coagulation factor deficiencies
What are the common features of a history of someone with a bleeding disorder?
Prolonged epistaxis (nosebleed)
Cutaneous haemorrhage or bruising with minimal or no trauma
Prolonged bleeding from trivial wounds
Oral cavity bleeding
Spontaneous gastrointestinal bleeding
Menorrhagia not associated with structural lesions of the uterus
What are the common acquired causes of a coagulopathy?
Vitamin K deficiency
Disseminated Intravascular Coagulation (DIC)
Liver disease
In the coagulation cascade, what is the purpose of factor VIII?
When converted into VIIIa, it enables the conversion of factor X into Xa. IXa must also be present for this to happen.
What are the two pathways of the coagulation cascade?
Contact activation (intrinsic) pathway
Tissue factor (extrinsic) pathway
What are the factors that make up the intrinsic (contact activation) pathway of the coagulation cascade?
XII - XIIa
XI - XIa
IX - IXa
VIII - VIIIa
What are the factors that make up the extrinsic (tissue factor) pathway of the coagulation cascade?
VII - VIIa
X - Xa
Tissue factor (III)
What are the factors that make up the common pathway of the coagulation cascade?
II (Prothrombin)
IIa (Thrombin)
V - Va
I (Fibrinogen)
Ia (Fibrin)
XIII - XIIIa
What does the activated partial thromboplastin time (APTT) represent?
Performance indicator of the efficacy of both the intrinsic (contact activation) pathway and the common coagulation pathway.
What does the prothrombin time (PT) represent?
Measure of the extrinsic pathway of coagulation.
What factor is deficient in haemophilia A?
VIII
What factor is deficient is haemophilia B?
IX
What is the prevalence of haemophilia A among males?
1 in 5000
What is the prevalence of haemophilia B among males?
1 in 25000
Below what percentage of factor VIII or IX are patients considered to have severe haemophilia?
Less than 1%
Within what range, as a percentage of factor VIII or IX, are patients considered to have moderate haemophilia?
1-5%
Above what percentage of factor VIII or IX are patients considered to have mild haemophilia?
> 5%