week 2

Question 1

requirements of haemostasis

Answer 1

permanent state of readiness
prompt response
localised response
protection against unwanted thrombosis

Question 2

lifespan of platelet

Answer 2

7-10 days

Question 3

function of a platelet

Answer 3

endothelial damage exposed collagen and releases von willebrand factor and other proteins to which platelets have receptors- platelet adhesion at the site of injury
secretion of various chemicals from the platelets leads to aggregation of platelets at the site of injury

Question 4

consequences of failure of platelet plug formation

Answer 4

spontaneous bruising and purpura
mucosal bleeding
- epistaxes
- GI
- conjunctival
- menorrhagia
intacranial haemorrhage
retinal haemorrhages

Question 5

failure of fibrin clot formation- causes

Answer 5

single clotting factor deficiency
- usually hereditary (haemophilia)
multiple clotting factor deficiencies
- usually acquired (DIC)
increased fibrinolysis
- usually part of complex coagulopathy

Question 6

naturally occurring anticoagulants

Answer 6

serine protease inhibitors
protein C and protein S

Question 7

failure of platelet plug formation- causes

Answer 7

vascular (hereditary of acquired)
platelets
- reduced number (thrombocytopenia)
- reduced function
von willebrand factor

Question 8

causes of thrombocytopenia

Answer 8

hereditary
acquired
- reduced production
- increased destruction

Question 9

causes of peripheral platelet destruction

Answer 9

coagulopathy: DIC
autoimmune: immune thrombocytopenic purpura
hypersplenism

Question 10

acquired platelet functional defects

Answer 10

drugs (aspirin, NSAIDs)
renal failure

Question 11

hereditary causes of thrombocytopenia

Answer 11

vWF deficiency

Question 12

multiple factor deficiencies leading to failure of fibrin clot formation

Answer 12

liver failure
vit K deficiency/warfarin therapy
complex coagulopathy: DIC

Question 13

screening tests for multiple factor deficiencies

Answer 13

prolonged prothrombin time and APTT

Question 14

where are coagulation factors synthesised

Answer 14

hepatocytes

Question 15

causes of vit K deficiency

Answer 15

poor dietary intake
malabsorption
obstructive jaundice
vit K antagonists- warfarin
haemorrhagic disease of the newborn

Question 16

causes of DIC

Answer 16

sepsis
obstetric emergencies
malignancy
hypovolaemic shock

Question 17

what is haemophilia A

Answer 17

factor VIII deficiency

Question 18

what is haemophilia B

Answer 18

factor IX deficiency

Question 19

screening test results in haemophilia

Answer 19

prolonged APTT
bleeding time, thrombin time, PT normal

Question 20

clinical presentation of severe haemophilia

Answer 20

recurrent haemarthroses
recurrent soft tissue bleeds
prolonged bleeding after dental extractions, surgery and invasive procedures

Question 21

most common inherited bleeding disorder

Answer 21

von willebrand’s disease

Question 22

role of von willebrand factor

Answer 22

large glycoprotein which forms massive multimers
promotes platelet adhesion to damage endothelium
carrier molecule for factor VIII

Question 23

investigation results for vWF

Answer 23

FBC-may be normal or may show microcytic anaemia or low platelet count
prolonged bleeding time
APTT may be prolonged
factor VIII levels may be moderately reduced

Question 24

management of vWF

Answer 24

tranexamic acid for mild bleeding
desmopressin: raises levels of vWF by inducing release of vWF from weibel-palade bodies in endothelial cells

Question 25

treatment of arterial thrombosis

Answer 25

aspirin and other anti-platelet drugs

Question 26

treatment of venous thrombosis

Answer 26

heparin/warfarin/ new oral anticoagulant

Question 27

treatment of ITP

Answer 27

• Prednisolone
• IV immunoglobulins
• Blood transfusionsif required
• Platelet transfusionsonly work temporarily

Question 28

clinical presentation of ITP

Answer 28

• Usually present in children under 10 years old
• Often there is a history of a recent viral illness
• The onset of symptoms occurs over 24-48 hours:
  
  • Bleeding, for example from the gums, epistaxis or menorrhagia
  • Bruising
  • Petechialorpurpuric rash, caused by bleeding under the skin

Question 29

pathophysiology of ITP

Answer 29

• Caused by atype II hypersensitivity reaction
  
  • It is caused by the production ofantibodies that target and destroyplatelets
  • This can happen spontaneously, or it can be triggered by something, such as a viral infection