Bleeding Disorders Flashcards

1
Q

What can cause failure of primary haemostasis (i.e. the platelet plug)?

A

Vascular
- e.g. lack of collagen

Platelets
- Reduced number or function

Von Willebrand Factor

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2
Q

What vascular abnormalities can cause failure of primary haemostasis?

A

Hereditary (weak collagen)

  • Marfan’s
  • Hyperflexibility Disorders

Acquired
Vasculitis
eg Henoch-Schonlein Purpura
(not actually problem with platelets, just leaky vessels)

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3
Q

What can cause a reduced NUMBER of platelets?

A

Decreased production
- Bone marrow problem

Increased Destruction (caused by:)

  • Disseminated Intravascular Coagulation (DIC)
  • Immune Thrombocytopenic Purpura (ITP)
  • Hypersplenism
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4
Q

What can decrease platelet function?

A

Drugs (eg Aspirin, NSAIDs)
- this is often deliberate (antiplatelets used to prevent arterial thrombosis in at risk patients)

Renal failure
- uraemia can interfere with platelet function

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5
Q

How is vWF deficiency normally inherited?

A

Autosomal dominant

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6
Q

If platelets are being prematurely destroyed, production of platelets increases in the bone marrow to compensate. What would the blood film look like if this was the case?

A

Large platelets
(larger on Day 1 than Day 7)
=> more large platelets = increased production

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7
Q

What are the main causes for failure of secondary haemostasis?

A

Multiple clotting factor deficiencies
- acquired (eg DIC)

Single clotting factor deficiency
- hereditary (eg Haemophilia)

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8
Q

What are the potential causes for multiple clotting factor deficiencies?

A
  • Liver failure (makes clotting factors)
  • Vitamin K Deficiency/Warfarin therapy (Vit K antag.)
    [Factor II, VII, IX, X all rely on Vit K]
  • Complex coagulopathy
  • DIC
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9
Q

Why may a platelet transfusion not be useful in patients who have increased destruction due to an autoimmune cause?

A

platelets will be destroyed by autoantibodies soon after they are given
- instead steroids should be used to suppress immune system and Ab

  • platelet transfusion may be more useful if marrow failure
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10
Q

If multiple clotting factors are affected, will PT or APTT be abnormal?

A

Both will be prolonged

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11
Q

Where do we find vitamin K and how is it absorbed?

A
  • Diet (green leafy veg)
    BUT can also be produced by bacteria in gut
  • Absorbed in upper intestine
  • Requires bile salts for absorption
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12
Q

What can cause a vitamin K deficiency?

A
  • Poor dietary intake
  • Malabsorption
  • Obstructive jaundice
  • Vitamin K antagonists (warfarin)
  • Haemorrhagic disease of the newborn (lack of vit K as none in breast milk, and not enough bacteria in bowel)
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13
Q

WHat is disseminated intravascular coagulation?

A
  • activation of clotting EVERYWHERE
  • Primary and secondary haemostasis and fibrinolysis
  • Microvascular thrombus formation => end organ failure
  • Clotting factors used up
    => Bruising, purpura
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14
Q

Using up all clotting factors has what effect on PT and APTT?

A

Prolonged (as body takes longer to clot if it cant find clotting factors)

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15
Q

Which of PT and APTT is first to become abnormal in DIC?

A

PT first as Factor VII has shortest T1/2

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16
Q

What can potentially cause DIC?

A
  • sepsis
  • obstetric emergencies
  • malignancy (chronic rather than rapid DIC)
  • hypovolaemic shock
17
Q

WHat types of malignancy are thought to cause DIC?

A

Adenocarcinomas

=> bowel or prostate cancers common

18
Q

HOw is DIC treated?

A
  • Treat the underlying cause
  • Replacement therapy
    Platelet / Plasma transfusions
    Fibrinogen replacement (especially if obstetric emergency)
19
Q

How is haemophilia inherited and which of Haemophilia A/B is more common?

A

X-linked Recessive
=> females carriers and males affected
females can be affected if inherit carrier gene and then gain another new mutation in utero

Haemophilia A 5x more common than Haemophilia B

20
Q

What symptoms are usually experienced by patients with haemophilias?

A
  • bleeding from medium to large vessels
    i. e. into joints/ muscles
  • Prolonged bleeding after dental extractions, surgery and invasive procedures
21
Q

Why are haemophilia patients more likely to get recurrent joint bleeds?

A
  • inflammation of synovium from initial joint bleed causes neovascularisation (new fragile blood vessels form)
  • these can then rupture and cause problems in the joint again
22
Q

What happens to the PT and APTT in haemophilia?

A

PT normal

APTT prolonged

23
Q

What treatment can be given to patients with haemophilia?

A

Factor VIII or IX concentrate to replace missing clotting factor

IV clotting factor VIII given every 2 days to start with (due to short T1/2)

  • often treatment starts when children start weight bearing on joints as this is when the joint bleeds start (Age 1 or 2)