Bleeding Disorders

Question 1

when is a fibrin clot added to a platelet plug?

Answer 1

when injury is more severe and plug needs stabilised

Question 2

what parts of the haemostatic system usually fail to cause bleeding disorders?

Answer 2

platelet plug (primary haemostasis)
fibrin clot (secondary haemostasis)

Question 3

3 main components of platelet plug?

Answer 3

vascular endothelial wall
platelets
von willebrand factor

Question 4

what platelet issues can cause problems forming platelet plug?

Answer 4

reduced number (thrombocytopaemia)
reduced function

Question 5

how to problems with VWF usually occur?

Answer 5

inherited

usually reduced amount

Question 6

what can cause vascular abnormalities?

Answer 6

hereditary (marfans syndrome, collagen problems etc)
acquired
- vasculitis (e.g Henoch schonlein purpura in children)
- scurvy (vit C deficiency causing collagen issues in vessel wall)

Question 7

where might purpura appear?

Answer 7

fundus
mouth
lower limb
across chest while coughing (during increased pressure)

Question 8

is thrombocytopaenia usually hereditary or acquired?

Answer 8

acquired

Question 9

causes of acquired thrombocytopaenia?

Answer 9

reduced production of platelets (bone marrow problem (leukaemia, lymphoma, infiltration etc)
increased destruction of platelets (often immune issue)

Question 10

clues of increased platelet destruction on blood film?

Answer 10

platelets get a lot smaller as they approach end of lifespan

Question 11

what can cause peripheral platelet destruction?

Answer 11

coagulopathy (DIC - lots of clotting and breakdown of clots uses up clotting factors, can occur in trauma eg RTA)
autoimmune (immune thrombocytopaenic purpura etc)
hypersplenism (platelets get trapped in spleen reducing overall platelet count)

Question 12

what can cause platelet problems when platelet count is normal?

Answer 12

platelet functional defects

can be hereditary or acquired (most commonly acquired)

Question 13

what can cause acquired platelet functional defects?

Answer 13

drugs (aspirin, NSAIDs, drugs used to prevent thrombosis)
renal failure (toxins e.g uraemia which build up in failing kidney can cause problems in platelets)

Question 14

Von Willebrand Factor (vWF) deficiency is usually hereditary or acquired?

Answer 14

hereditary

- autosomal dominant

Question 15

how will vWF deficiency present?

Answer 15

usually mild
mucosal bleeding (nose bleeds, bleeding gums, menorrhagia etc)

Question 16

commonest cause of primary haemostatic failure?

Answer 16

thrombocytopaenia
usually acquired (e.g marrow failure or peripheral destruction)

Question 17

what usually causes multiple clotting factor deficiency (failure of formation of fibrin clot)?

Answer 17

generally acquired (Eg complex coagulopathy such as DIC - clotting factors used up faster than you can make them, so clotting problem then becomes bleeding problem)
can be due to liver failure
vit K deficiency/warfarin therapy

Question 18

what can cause DIC?

Answer 18

trauma

sepsis

Question 19

what usually causes single clotting factor deficiency (failure of formation of fibrin clot)?

Answer 19

generally hereditary (e.g haemophilia)

Question 20

why does liver failure cause multiple clotting factor deficiency?

Answer 20

CFs all made in hepatocytes of liver

Question 21

which clotting factors need vitamin K?

Answer 21

2, 7, 9 and 10 are carboxylated by vit K

- therefore vit K deficiency can cause deficiency and bleeding problem

Question 22

vit K sources?

Answer 22

diet
bacteria in the bowel synthesis vit K
- babies don’t have the bacteria so need a vit K injection at birth to prevent bleeding (haemorrhagic disease of newborn)

Question 23

where is vit K absorbed?

Answer 23

upper intestine

required bile salts

Question 24

causes of vit K deficiency?

Answer 24

poor dietary intake (lack of green leafy veg)
malabsorption
obstructive jaundice
vit K antagonists (warfarin)
haemorrhagic disease of newborn

Question 25

what is disseminated intravascular coagulation?

Answer 25

tissue damage leading to excessive and inappropriate activation of all aspects of the haemostatic system (primary, secondary and fibrinolysis)
first response to damage leads to microvascular thrombus formation causing end organ failure (kidneys, lungs etc)
body then tries to break down all the clots while more clots continue to form
clotting factors are used up quickly leading to bruising, purpura and generalised bleeding

Question 26

which clotting factor has the shortest lifespan?

Answer 26

CF 7

- therefore prothrombin time tested first as CF 7 will be the first one affected if theres a problem

Question 27

causes of DIC?

Answer 27

sepsis
obstetric emergencies (abruption)
malignancy (tends to be more chronic and slow progressive, common in adenocarcinoma and bowel cancer)
hypovolaemic shock

Question 28

how is DIC managed?

Answer 28

treat underlying cause
replacement therapy
- platelet transfusions
- plasma transfusions
- fibrinogen replacement (cryoprecipitate)

Question 29

what is haemophilia?

Answer 29

hereditary disorder in which abnormally prolonged bleeding recurs episodically at one or a few sites on each occasion
causes fragile blood vessels?
lack of CF 8 or 9

Question 30

how is haemophilia inherited?

Answer 30

X linked (only affects males)

Question 31

types of haemophilia?

Answer 31

A = CF 8 deficiency (5X more common)
B = CF 9 deficiency

Question 32

problems in haemophilia?

Answer 32

no abnormality of primary haemostasis
- can form platelet plug fine so small cuts (e.g paper cut isn’t affected)
large bleeding from medium to large blood vessels
can be mild-mod-severe depending on level of CF8/9

Question 33

screening tests in haemophilia?

Answer 33

prothrombin time is normal (TF, CF7, CF5 and CF10 are normal)
very prolonged activated partial thromboplastin time

Question 34

clinical features of haemophilia?

Answer 34

recurrent haemarthroses
recurrent soft tissue bleeds (bruising in toddlers etc)
prolonged bleeding after dental extractions, surgery and invasive procedures

Question 35

how can haemophilia be managed?

Answer 35

IV clotting factor every second day