Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Haematology > 8. Abnormalities of haemostasis > Flashcards

8. Abnormalities of haemostasis Flashcards

1
Q

What are common causes of minor bleeding?

A
  • Family history
  • Easy bruising
  • Gum bleeding
  • Frequent nosebleeds
  • Bleeding after tooth extraction
  • Post-operative bleeding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the common causes of minor bleeding, in women?

A
  • Menorrhagia

* Post-partum bleeding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When would bleeding be considered abnormal?

A
  • Epistaxis (nosebleed) not stopped by 10 minutes of compression
  • Cutaneous haemorrhage or bruising without apparent trauma
  • Prolonged (>15min) bleeding from trivial wounds recurring spontaneously in 7 days after wound
  • Spontaneous GI bleeding => anaemia
  • Menorrhagia requiring treatment or => anaemia, (not due to structural lesions)
  • Heavy, prolonged bleeding after surgery/dental extractions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What usually causes abnormal haemostasis?

A

• Lack of specific factor (quantitative defect)

  • failure of production: congenital and acquired
  • increased consumption/clearance

• Defective function of a specific factor (qualitative defect)

  • genetic defect
  • acquired defect e.g. drugs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What can lead to disorders of primary haemostasis?

A

Problems with platelets
• Low numbers - bone marrow failure, accelerated clearance, pooling and destruction in enlarged spleen
• Impaired function - acquired due to drugs e.g. NSAIDs, hereditary absence of glycoproteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Name a common cause of thrombocytopenia

A

Auto-Immune Thrombocytopenic Purpura (auto-ITP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How are platelets ‘sensitised’?

A

• By platelet autoantibodies coating them

• whole complex cleared by the reticulo-endothelial system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Name 3 diseases/causes of hereditary platelet defects

A
  • Glanzmann’s thrombasthenia - lack of GpIIb/IIIa, autosomal recessive
  • Bernard Soulier syndrome - lack of Gp1b, autosomal recessive
  • Storage pool disease - broad term, issues with granular storage and release
  • Glycoproteins are important in reversible adhesion to surfaces, and irreversible adhesion to each other
  • Disorder => problems with primary haemostasis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What causes Von Willebrand disease?

A
  • Hereditary decrease of quantity and function
  • Acquired due to antibody (acquired vW syndrome)
  • Can’t initiate primary haemostasis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the 2 functions of vWF in haemostasis?

A
  • Binding to collagen and capturing platelets

* Stabilising factor VIII

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What can causes problems with the vessel wall (leading to disorders of primary haemostasis)?

A
  • Inherited - hereditary haemorrhagic telangiectasia, Ehlers-Danlos syndrome and other connective tissue disorders
  • Acquired defects - scurvy, steroids, ageing, vasculitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are petechiae?

A
  • Small blood spots in thrombocytopenia
  • Appear spontaneously
  • Pathognomonic sign of low platelet count
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How can you test for disorders of primary haemostasis?

A
  • Platelet count, morphology
  • Bleeding time
  • Assays of vWF
  • Clinical observation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the role of the coagulation cascade in secondary haemostasis?

A
  • Generate a burst of thrombin
  • This converts fibrinogen into fibrin
  • Necessary in larger vessels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What can you use to illustrate thrombin generation?

A

Thrombogram

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Summarise the causes of secondary haemostasis disorders

A
  • Deficiency of coagulation factors - hereditary failure of production, acquired
  • Increased consumption (acquired) - DIC, immune autoantibodies
17
Q

Why does haemophilia cause problems with bleeding?

A
  • Have collagen vWF and platelets, so primary platelet plug is formed
  • Factor 8 or 9 affected
  • Not enough thrombin produced - plug will fall apart
  • Delayed bleeding
18
Q

How does liver disease affect secondary haemostasis?

A
  • Most coagulation factors synthesised in the liver

* However, anticoagulants are also made in the liver, so this tends to balance out

19
Q

What are the acquired causes of defects in secondary haemostasis?

A
  • Liver disease
  • Drugs (warfarin)
  • Dilution (red cell transfusions - without plasma)
  • Consumption (DIC)
20
Q

How serious are different coagulation factor deficiencies?

A
  • Factor 8 + 9 (haemophilia) - severe but compatible with life
  • Factor 2 (prothrombin deficiency) - lethal
  • Factor 11 - bleed after trauma, not spontaneous
  • Factor 12 - no excess bleeding at all
21
Q

What causes disseminated intravascular coagulation (DIC)?

A
  • aka consumptive coagulopathy
  • Generalised activation of coagulation - tissue factor is triggered - uncontrolled
  • Consumes and depletes coagulation factors and platelets
  • Activation of fibrinolysis depletes fibrinogen - increases fibrin degradation products (FDPs)
  • Deposition of fibrin in vessels causes organ failure
  • Associated with sepsis, obstetric causes, major tissue damage and inflammation
22
Q

What are the consequences of DIC?

A
  • Widespread bleeding from IV lines, bruising + internal

* Organ failure

23
Q

Outline the patterns of bleeding in problems with secondary haemostasis?

A
  • Often delayed
  • Prolonged, stop-start
  • Deeper: joints and muscles
  • Bruising
  • Delayed, prolonged bleeding after trauma/surgery
  • Bleeding after IM injections
  • Nosebleeds are rare
  • Superficial cuts don’t bleed due to platelets - primary is ok
24
Q

What is the hallmark of haemophilia?

A

Haemarthrosis - bleeding into the joints
• pressure builds up
• joint becomes swollen and painful

25
Q

How can you test for disorders of secondary haemostasis (coagulation disorders)

A
  • Screening tests - PT, APTT, full blood count
  • Factor assays
  • Test for inhibitors
26
Q

What is the APTT and PT in haemophilia?

A
  • APTT - prolonged, not making factor 8 or 9

* PT - normal - extrinsic pathway not affected

27
Q

Which bleeding disorders are not detected by routine clotting tests?

A
  • Mild factor deficiencies
  • vW disease
  • Factor 13 deficiency
  • Platelet disorders
  • Excessive fibrinolysis
  • Vessel wall disorders
  • Metabolic disorders
28
Q

What are the hereditary and acquired disorders of fibrinolysis?

A
  • Hereditary - antiplasmin deficiency

* Acquired - drugs (e.g. tPA), DIC

29
Q

Outline the genetics of haemophilia and vW disease?

A

Haemophilia
• X-linked recessive
• Disease tends to be carried by females, and affects males
• Varying degrees of lyonization

vW disease
• Autosomal
• Type 1 + 2 - autosomal dominant
• Type 3 (and the rest) - autosomal recessive (rare)

30
Q

How do you treat abnormal haemostasis, with references to general causes

A
  • Failure of production - replace missing factor/platelets, stop drugs causing it
  • Immune destruction - immunosuppression, splenectomy for ITP
  • Increased consumption - treat the cause of the DIC, replace what is missing
31
Q

What can factor replacement therapy involve?

A

• Plasma - contains all coagulation factors
• Cryoprecipitate - rich in fibrinogen, factor 8 + 13, vWF
• Factors concentrates
- all factors except factor 5
- prothrombin complex concentrates (PCCs): factors 2, 7, 9, 10
• Recombinant forms of factor 8 and 9 available

32
Q

How could haemophilia be treated (in the future)?

A

Gene therapy

33
Q

What novel approaches are there in development for haemostatic disorders?

A
  • Bispecific antibodies
  • Anti-TFPI antibodies
  • Antithrombin RNAi
34
Q

How can desmopressin (DDAVP) act as a haemostatic treatment?

A
  • Vasopressin derivative
  • Causes 2-5 fold rise in vWF and factor 8
  • Causes released from endogenous stores - only useful in mild disorders
  • Can be given as a nasal spray (300μg) or IV (0.3μg/kg)
35
Q

How can tranexamic acid act as a haemostatic treatment?

A

• Inhibits fibrinolysis (binding of tPA to fibrin)
• Widely distributed, crosses placenta, low conc. in breast milk
• Adjunctive therapy
- IV: 0.5g tds (three times a day)
- oral: 1.5g tds
- mouthwash: 1g (10ml 5%) qds (four times a day)

Haematology (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions