Haemostasis

Question 1

principles of haemostasis

Answer 1

normal number and function of platelets
functional coagulation cascade
normal vascular endothelium

Question 2

what are the 3 stages of formation of a platelet rich thrombus

Answer 2

platelet adhesion
platelet activation/secretion
platelet aggregation

Question 3

what converts fibrinogen to fibrin

Answer 3

thrombin

Question 4

what stabilises the platelet thrombus

Answer 4

polymerisation of fibrin

Question 5

what do platelet and vessel wall defects give rise to

Answer 5

prolonged bleeding time

Question 6

causes of thrombocytopenia

Answer 6

bone marrow failure
peripheral consumption

Question 7

causes of abnormal platelet function

Answer 7

most commonly drugs - aspirin, clopidogrel
renal failure - uraemia causes platelet dysfunction

Question 8

causes of abnormal vessel walls

Answer 8

scurvy
ehlers danlos syndrome
henoch schonlein purpura
hereditary haemorrhagic telangiectasia

Question 9

causes of abnormal interaction between platelets and vessel wall

Answer 9

von willebrand disease

Question 10

drugs inhibiting platelet function

Answer 10

aspirin and COX inhibitors
reversible COX inhibitors - e.g. NSAIDs
dipyridamole
thienopyridines
integrin GP2b/3a receptor antagonists

Question 11

coagulation pathways - intrinsic pathway

Answer 11

12 > 12a
11> 11a
9 > 9a, 8a

Question 12

coagulation pathways - extrinsic pathway

Answer 12

10 > 10a, 5a

Question 13

coagulation pathways - common pathway

Answer 13

2 > 2a
fibrinogen > fibrin

Question 14

factor 12 deficiency

Answer 14

dont bleed

Question 15

factor 7 deficiency

Answer 15

bleed abnormally

Question 16

factor 8 and 9 deficiency

Answer 16

severe haemorrhagic diathesis despite normal extrinsic coagulation pathway

Question 17

factor 11 deficiency

Answer 17

variable and mild bleeding diathesis

Question 18

overlapping steps leading to coagulation

Answer 18

initiation
amplification
propagation
termination

Question 19

what prevents over activity of coagulation cascade

Answer 19

natural inhibitors

Question 20

what does tissue factor pathway inhibitor inhibit

Answer 20

TF-7a complex/f10a inhibited by TFPI

Question 21

what does antithrombin inhibit

Answer 21

thrombin and f10a activity

Question 22

what does protein c pathway inhibit

Answer 22

f5a and f8a

Question 23

prothrombin time

Answer 23

measured in seconds
reflects extrinsic pathway and common pathway

Question 24

activated partial thromboplastin time

Answer 24

measured in seconds
reflects intrinsic pathway and common pathway

Question 25

fibrinogen lab measurement

Answer 25

measured in grams/L reflects functional activity of fibrinogen protein

Question 26

f12 defect inheritance

Answer 26

autosomal

Question 27

f11 defect inheritance

Answer 27

autosomal

Question 28

f9 defect - haemophilia B inheritance

Answer 28

x-linked recessive

Question 29

f8 defect - haemophilia A inheritance

Answer 29

x-linked recessive

Question 30

von willebrand disease inheritance

Answer 30

autosomal dominant

Question 31

f7 defect inheritance

Answer 31

autosomal recessive

Question 32

f10, 5, 2, 1 and 13 defect inheritance

Answer 32

autosomal recessive

Question 33

haemophilia A

Answer 33

x linked recessive - typically expressed in males and carried in females deficiency/dysfunction of f8

Question 34

traditional management of haemophilia

Answer 34

supportive measures - ice, immobilisation, rest replacement of missing clotting protein antifibrinolytic agents

Question 35

congenital haemophilia

Answer 35

haemarthroses muscle bleeds soft tissue bleeds

Question 36

acquired haemophilia

Answer 36

large haematomas gross haematuria retropharyngeal and retroperitoneal haematomas cerebral haemorrhages compartment syndromes

Question 37

roles of von willebrand factor

Answer 37

promote platelet adhesion to subendothelium at high shear rates carrier molecule for f8

Question 38

von willebrand disease

Answer 38

mainly autosomal dominant inheritance men and women affected associated with defective primary haemostasis variable reduction in f8 levels - mucocutaneous bleeding including menorrhagia, post-op/post partum bleeding

Question 39

von willebrand management

Answer 39

antifibrinolytics DDAVP factor concentrates containing vWf contraceptive pill for menorrhagia

Question 40

acquired coagulation disorders

Answer 40

underproduction of coagulation factors - liver failure, vit K deficiency anticoagulants - warfarin, direct oral anticoagulants immune - acquired haemophilia, acquired VWD consumption of coagulation factors

Question 41

effect of liver disease of haemostasis

Answer 41

reduced hepatic synthesis of clotting factors thrombycytopaenia secondary to hypersplenism reduced vit K absorption due to cholestatic jaundice causing deficiencies of f2, 7, 9 and 10 - warfirin treated with plasma products and platelets to cover procedures, and vit K

Question 42

disseminated intravascular coagulation (DIC)

Answer 42

acquired syndrome - systemic intravascular activation of coagulation - thrombin explosion widespread deposition of fibrin in circulation tissue ischaemia and multi-organ failure consumption of platelets and coagulation factors to generate thrombin - may induce severe bleeding excess plasmin generated to maintain vascular patency, leads to fibrinogenolysis

Question 43

DIC coagulation parameters

Answer 43

prolonged prothrombin time prolonged activated partial thromboplastin time low fibrinogen raised d-dimers - marker of increased fibrinolysis