haemostasis

Question 1

what are the principles of haemostasis

Answer 1

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

Question 2

3 stages of generation of the haemostatic plug

Answer 2

platelet adhesion
platelet activation/secretion
platelet aggregation

Question 3

what is converted during coagulation and by what

Answer 3

fibrinogen to fibrin by thrombin

Question 4

what stabilises the platelet thrombus

Answer 4

polymerisation of fibrin

Question 5

primary and secondary parts of hemostatic plug formation

Answer 5

primary - aggregation
secondary - coagulation

Question 6

2 types of platelet defects

Answer 6

reduced number of platelets
abnormal platelet function

Question 7

causes of abnormal platelet function

Answer 7

drugs such as aspirin and clopidogrel
renal failure

Question 8

2 types of vessel wall defects?

Answer 8

abnormal vessel wall
abnormal interaction between platelets and vessel wall

Question 9

causes of abnormal vessel wall - scurvy?

Answer 9

causes bruising and bleeding as inadequate vitamin C so cant produce collagen which is needed for epithelial layer

Question 10

what type of haemorrhage occurs in scurvy

Answer 10

peri-follicular haemorrhage - bleed around hair follicle, follicle becomes corkscrew shaped due to lack of vitamin C

Question 11

what does HHT stand for? what is abnormal?

Answer 11

hereditary haemorrhagic telangiectasia, abnormal vessel wall

Question 12

HHT presentation

Answer 12

many capillaries on skin surface bleeding

Question 13

drugs that inhibit platelet function examples

Answer 13

aspirin and COX inhibitors
reversible COX inhibitors (eg NSAIDS)

Question 14

what is the name for bleeding into the skin that is non blanchable

Answer 14

purpura

Question 15

what is ecchymosis

Answer 15

medical term for a bruise

Question 16

name for discoloration of skin that doesn’t turn white when pressed

Answer 16

nonblanchable

Question 17

what is IIa

Answer 17

thrombin

Question 18

at which clotting factor does the intrinsic and extrinsic pathway merge

Answer 18

Xa (clotting factor 10)

Question 19

commonest causes of congenital haemophilia

Answer 19

problems with factor 8 and factor 9 (cofactors)

Question 20

coagulation cascade requirements?

Answer 20

right temperature, calcium present

Question 21

why do hypothermic patients bleed

Answer 21

wrong temperature so clotting factors don’t optimally function

Question 22

what do extrinsic and intrinsic factors do

Answer 22

convert X (inactive clotting factor 10) to Xa (active clotting factor 10)

Question 23

what does Xa form? what does it need for this to occur?

Answer 23

prothrombinase.
requires Calcium, factor 5a, phospholipid surface membrane

Question 24

what does prothrombinase do

Answer 24

converts II to IIa (thrombin)

Question 25

which pathway is slow/fast?

Answer 25

extrinsic tenase - fast intrinsic tenase - slow

Question 26

what does intrinsic tenase do?

Answer 26

enables layers of thrombin to be generated and a fibrin clot to be consolidated, stops the first little clot by extrinsic tenase being washed away.

Question 27

what happens to clotting factors in haemophilia

Answer 27

not enough factor 8 or 9, or wrong proportions of 8 and 9, resulting in an unstable clot.

Question 28

do haemophiliacs bleed if you take their blood

Answer 28

no! their platelets work, their extrinsic pathway still works, but not their intrinsic - so they will bleed later on

Question 29

4 steps leading to coagulation

Answer 29

initiation amplification propagation termination

Question 30

what inhibits TF-VIIa complex/fXa?

Answer 30

tissue factor pathway inhibitor (TFPI)

Question 31

what inhibits thrombin an fXa?

Answer 31

antithrombin

Question 32

what inhibits fVa and fVIIIa

Answer 32

protein C pathway

Question 33

what happens when a patient is vitamin C deficient

Answer 33

generates too much thrombin leading to skin necrosis

Question 34

laboratory measurements (coagulation screen)?

Answer 34

Prothrombin time (PT) Activated Partial Thromboplastin Time (APTT) Fibrinogen

Question 35

what is prothrombin time (PT) measured in and reflecting

Answer 35

reflects extrinsic and common pathway measured in seconds

Question 36

what is the APTT measured in and reflecting

Answer 36

reflects intrinsic and common pathway measured in seconds

Question 37

what is fibrinogen lab measurement measured in and reflecting

Answer 37

measured in grams/L reflects functional activity of the fibrinogen protein

Question 38

haemophilia A defect and inheritance

Answer 38

VIII X-linked recessive

Question 39

haemophilia B defect and inheritance

Answer 39

IX X-linked recessive

Question 40

what are 30% of haemophilia A cases?

Answer 40

sporadic mutations - no family history

Question 41

haemophilia A clinical cases

Answer 41

traumatic bleed (mild) spontaneous bleed (severe haemophilia) chronic arthropathy (recurrent bleeding into joints)

Question 42

haemophilia management

Answer 42

ice, immobilisation, rest (joints) replacement of missing protein antifibrinolytic agents

Question 43

what is the name for bleeding into weight bearing joints

Answer 43

hemarthroses

Question 44

most common hereditary bleeding disorder

Answer 44

von Willebrand disease

Question 45

what type of bleeding occurs in von Willebrand disease

Answer 45

mucocutaneous bleeding - nose bleeds, mucosal bleeding, gum bleeding, rectal bleeding, menorrhagia (menstrual bleeding lasting more than 7 days)

Question 46

inheritance of Von Willebrand Disease

Answer 46

autosomal dominant

Question 47

Von Willebrand Disease management

Answer 47

antifibrinolytics (tranexamic acid) DDAVP contraceptive pill for menorrhagia

Question 48

acquired clotting disorders types?

Answer 48

underproduction of coagulation factors anticoagulants immune consumption of coagulation factors

Question 49

acquired causes of underproduction of coagulation factors

Answer 49

liver failure vitamin K deficiency

Question 50

anticoagulant drug example that cause coagulation disorders

Answer 50

warfarin

Question 51

immune causes of acquired coagulation disorders

Answer 51

acquired haemophilia and VW syndrome

Question 52

what occurs in relation to clotting factors in liver disease

Answer 52

reduced hepatic synthesis of clotting factors

Question 53

liver disease - complication of hypersplenism?

Answer 53

thrombocytopenia

Question 54

liver disease - what does cholestatic jaundice cause

Answer 54

reduced vitamin K absorption causing deficiencies of factors II, VII, IX, and X

Question 55

vitamin K dependant clotting factors?

Answer 55

II, VII, IX, X (2, 7, 9, 10)

Question 56

monoclonal antibody which mimics factor 8?

Answer 56

emicizumab

Question 57

what does DIC stand for

Answer 57

disseminated intravascular coagulation

Question 58

what is DIC?

Answer 58

clotting pathways don't work anymore. it is a syndrome. found in patients that are critically ill

Question 59

is DIC acquired or inherited?

Answer 59

acquired

Question 60

what occurs in DIC

Answer 60

thrombin explodes into action - too much generated or not enough regulation deposition of fibrin in circulation tissue ischaemia and multi-organ failure severe bleeding

Question 61

what causes DIC (7)

Answer 61

sepsis, tumour, trauma, toxic, vascular, pancreatitis, obstetric (amniotic fluid in internal circulation)

Question 62

what can show in peripheral blood films for a patient with DIC

Answer 62

red cell fragments

Question 63

DIC coagulation parameters?

Answer 63

prolonged PT prolonged APTT low fibrinogen raised D-dimers

Question 64

what are D-dimers

Answer 64

fibrinogen degradation products