Bleeding Disorders and Coagulopathies Flashcards
Where does heparin work?
Multiple sites, including intrinsic system
How is warfarin measured?
INR
How is heparin measured?
Platelet count
What does APTT measure?
Heparin
Factor VIII
Factor IX
What constitutes a coagulation profile?
Platelet count
APTT
PT
What tests can measure dabigatran levels?
Thrombin clotting time (TCT)
Drug levels
What tests can measure rivaroxaban and apixaban levels?
Anti-Xa levels
What is a common treatment if a person is too anticoagulated?
Prothrombinex
What is the lifespan of platelets?
8-9 days
How can the effects of clopidogrel and aspirin be reversed?
Platelet transfusion
If platelet transfusion fails, what else can be done to reverse the effects of clopidogrel and aspirin?
Desmopressin
Recombinant factor VIIa
What is the clinical evaluation of bleeding disorders?
Age at onset Spontaneous/post-traumatic Sites/frequency of bleeds/quantitation of bleeding Bleeding stressors; eg: - Tooth extractions - Surgery FHx Medications Therapy received and response Convincing evidence of "excessive bleeding"
What does von Willebrand factor do?
Mediates platelet adhesion at site of injury
Stabilises factor VIII in circulation
What is type 1 von Willebrand disease?
Partial vWF deficiency
What is type 2 von Willebrand disease?
2A - decreased affinity of vWF for platelets due to decrease in multimers
2B - increased affinity of vWF for platelets due to vWF mutation > thrombocytopaenia
2M - decreased platelet binding due to vWF mutation
2N - defective factor VIII binding site > decreased factor VIII levels
What is type 3 von Willebrand disease?
Complete vWF deficiency
When is von Willebrand disease treated?
Only if symptomatic, rarely prophylactically
What is the treatment of von Willebrand disease?
Desmopressin - Useful for minor procedures - Effective in type 1 - Causes hyponatraemia Replacement therapy
What is the symptomatic treatment of von Willebrand disease?
Antifibrinolytics - inhibit fibrinolysis > prolong thrombus formation time
- TXA
Oral contraceptives/Mirena to manage periods
Fibrin glue - for nosebleeds
What are the investigations for von Willebrand disease?
May be mildly elevated APTT Initial tests - Factor VIII levels - vWF Ag levels - vWF activity/function test - Blood group - group O have lower levels More specialised tests to subtype
What are the investigations for haemophilia?
Hb May be mildly elevated APTT Normal INR Initial tests - Factor VIII and IX levels - Likely to be levels of 5-30% Genetic studies
What are the clinical manifestations of haemophilia A?
Haemarthrosis Subcutaneous and IM haematomas Psoas and retroperitoneal haematomas Traumatic bleeding - Delayed bleeding, especially in tooth extractions - Slow wound healing
What is the course and prognosis of haemophilia A?
Nearly normal lifespan with factor VIII replacement
What are the differential diagnoses for haemophilia A?
Haemophilia B
von Willebrand’s disease, especially type 2N
What is the treatment for haemophilia A?
Factor VIII replacement
- Prophylactically in children with severe form
Desmopressin, if mild
What is the course and prognosis of haemophilia B?
Nearly normal lifespan with factor IX replacement
Which of the two is more prevalent: haemophilia A or B?
A
What is the treatment for haemophilia B?
Prothrombinex
Recombinant factor IX therapy
- Given prophylactically in children with severe form
What are the investigation results in immune thrombocytopaenia purpura?
Thrombocytopaenia
Abs to several surface platelet Ags
What is the treatment for immune thrombocytopaenia purpura?
Initially high dose steroids Avoid platelet transfusions IV Ig if bleeding Further treatments - Splenectomy
What sort of bleeding occurs in thrombocytopaenia?
Skin and mucous membranes - Petechiae - Ecchymosis - Haemorrhagic vesicles - Gingival bleeding and epistaxis Menorrhagia GI bleeding Intracranial bleeding
What is the investigation conducted when APTT is prolonged?
Mixing study = equal parts normal pooled plasma added to patient plasma
Significant correction > factor deficiency
No correction > inhibitor present
What further tests are indicated if there is correction of APTT in a mixing study?
Specific factor assays
- VIII
- IX
- XI
- XII
What further tests are indicated if there is no correction of APTT in a mixing study?
Lupus anticoagulant
What effect does lupus anticoagulant have on clotting?
In vivo - increases clotting
In vitro - increases bleeding
What effect does quinine have on clotting?
Can induce lupus inhibitors
What happens in consumptive coagulopathy?
Severe bleeding > all coagulants used up > bleeding
What will normal screening tests miss?
Mild von Willebrand’s disease
Mild haemophilia
Factor XIII deficiency
Platelet function disorders
