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Minor Oral Surgery > Bleeding disorders seen in the dental practice > Flashcards

Bleeding disorders seen in the dental practice Flashcards

1
Q

What is the function of both intrinsic and extrinsic coagulation pathways?

A

activation of factor V

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2
Q

What is the function of activated factor V (Xa)?

A

cleaves prothrombin to release thrombin

(thrombin catalyses formation of fibrin clot)

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3
Q

What is the result of the activation of coagulation inhibitors?

A

restrict coagulation to the site of injury

  • prevention of pathological coagulation
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4
Q

How can platelet disorders be described?

A
  • quantitative
  • qualitative
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5
Q

Give examples of inherited qualitative/quantitative platelet disorders

A
  • bernard soulier disease
  • glazmanns thrombasthenia
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6
Q

Give examples of acquired platelet disorders

A
  • altered platelet function due to aspirin or NSAID intake
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7
Q

Outline some clinical presentations of platelet disorders

A
  • purpura
  • petechiae
  • mucosal bleeding
  • epistaxis
  • menorrhagia
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8
Q

What is the difference between purpura and petechiae?

A
  • purpura measures between 4-10 mm
  • petechiae <4mm
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9
Q

Give examples of inherited clotting cascade disorders

A
  • haemophilia A and B
  • Von williebrands disease
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10
Q

Give an examples of acquired clotting cascade disorder

A
  • disseminated intravascular coagulation (DIC)
  • Liver disease
  • vitamin K deficiency
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11
Q

What signs should a dental surgeon be looking out for to aid assessment of a patients bleeding tendency?

A
  • bruises, ecchymyosis, haematomas - history, causes, frequency, ease of bruising, drug and family history
  • petechiae, purpura, swollen joints- history, causes, other bleeding sites e.g. gingivae
  • signs of systemic disease such as tachycardia, hypertension , heart disease, impaired hepatic function, spontaneous plaque-free gingival bleeding
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12
Q

Spontaneous, plaque-free gingival bleeding could be an early sign of …

A

leukaemia

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13
Q

Prothrombin time evaluates …

A

extrinsic pathway

(II, V, VII, X and fibrinogen)

2, 5, 7, 10

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14
Q

What are the normal values for prothrombin time ?

A

12-15 seconds

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15
Q

Prothrombin time is prolonged in …

A
  • warfarin treatment
  • liver disease
  • vitamin K deficiency
  • DIC

vitamin K clotting factors, 2, 7, 9, 10

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16
Q

INR evaluates …

A

extrinsic pathway of blood coagulation (II, V, VII, X, fibrinogen)

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17
Q

What are the normal values for INR?

A

About 1.0
(0.8-1.2) )

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18
Q

INR is prolonged in …

A
  • warfarin treatment
  • liver disease
  • vitamin K deficiency
  • DIC
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19
Q

APTT (activated partial thromboplastin time) evaluates …

A

intrinsic pathway
which includes factor II, V and X

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20
Q

What are the normal values for APTT?

A

25 (+/- 10) seconds

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21
Q

Prolonged APTT occurs in what instances?

A
  • heparin treatment
  • liver diseae
  • haemophilia
  • DIC
  • massive transfusion
  • some auto-immune treatments such as lupus anticoagulant
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22
Q

What does thrombin time evaluate?

A

the abnormality in converting fibrinogen (soluble protein) to fibrin (an insoluble protein)

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23
Q

What are the normal thrombin time values?

A

10-15 seconds

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24
Q

Thrombin time is prolonged in …

A
  • heparin treatment
  • DIC
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25
Q

What is the function of “bleeding time” ?

A

assess platelet and normal blood vessel function

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26
Q

What is the normal value of bleeding time?

A

2-9 minutes

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27
Q

The value of bleeding time depends on …

A

method used (to achieve bleeding?)
Ivy or Duke

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28
Q

Bleeding time is prolonged in …

A
  • platelet disorders
  • vessel wall disorders
  • fibrinogen disorders
  • von willibrands disease
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29
Q

How is the INR calculated ?

A

it is a ratio of the patients PT (prothrombin time) to a normal control

30
Q

What is the advantage of the INR over the PT?

A

it uses international standards and thus the anti-coagulant control can be compared in different hospitals and clinics around the world

31
Q

What is the normal platelet count ?

A

150 000- 450 000 platelets per microlitre

32
Q

How are bleeding disorders generally categorised?

A
  • coagulation disorders
  • vascular defects
  • Platelet defects (number or structural defects)
  • fibrinolytic defects
33
Q

Studies have shown that it is safe for patients on low-dose aspirin, clopidogrel and dipyridamole to remain on these medications if they require minor oral surgery. True or false

A

True

34
Q

What are the functions of von willie brands factor?

A
  • essential cofactor for normal platelet adhesion to damaged subendothelium- forms the bridge that allows platelets to adhere to damaged endothelial surfaces
  • serves as a carrier for factor VIII for form the whole factor VIII comple- stabilise circulating factor VIII
35
Q

What is the benefit of factor VIII complex formation?

A

protection from inactivation and clearance

36
Q

What is the most common inherited bleeding disorder?

A

von williebrands disease

37
Q

What is the pattern of inheritance of von williebrands disease?

A

autosomal dominant

38
Q

Expression/presentation of von williebrands disease varies. True or false

A

True

39
Q

What tests are impacted by von williebrands disease ?

A
  • APTT
  • Clotting time
  • Bleeding time
40
Q

Patients with VWD may suffer from deep seated haemorrhages. What is the cause of this?

A

factor VIII deficiency

(remember VWF is carrier for factor VIII)

41
Q

What is the impact of VWD on prothrombin time?

A

remains normal

42
Q

What is the impact of VWD on Thrombin time?

A

remains normal

43
Q

What is the impact of VWD on platelet count?

A

remains normal

44
Q

What is the impact of VWD on a factor VIII?

A

factor VIII assay is usually reduced

45
Q

A tourniquet test for patients with VWD is usually _______.

A

positive

46
Q

Type 1 VWD is considered to be a ______ defect. What is the pattern of inheritance

A

quantitative defect

autosomal dominant

47
Q

How is type 1 VWD usually confirmed?

A
  • abnormal platelet function tests
  • decrease in VWF antigen
  • proportional decreae in factor VIII activity
48
Q

Type II VWD is a ____ defect.

A

qualitative

49
Q

What are the subtypes of type II VWD? Outline their patterns of inheritance

A
  • A
  • B
  • M
  • N

They are all autosomal dominant

50
Q

What is the pattern of inheritance for type III VWD?

A

autosomal recessive

very severe but rare

51
Q

What is the most common type of VWD?

A

Type I
(70% of cases)

52
Q

What is the clinical presentation of VWD?

A

resembles classic haemophilia

53
Q

What treatment is offered for VWD?

A

desmopressin which raises VWF levels in mild diseae

raises factor VIII/VWF concentrates in more severe disease

54
Q

Why does an affected male with haemophilia not transmit the disease to his son ?

A

this is because the Y chromosome does not carry the haemophilic gene

55
Q

A small proportion of female carriers of haemophilia may bleed significantly. True or false

A

True

56
Q

What are the general clinical presentations of haemophilia?

A
  • bruisinh
  • muscle and joint haemorrhages
  • prolonged haemorrhage after surgery or trauma (no excessive bleeding after minot cuts)
57
Q

What is the clinical presentation of severe haemophilia?

A

spontaneous bleeding into large muscles and joints unless regular treatment with factor VIII concentrate is given

58
Q

When is factor VIII administered in mild and moderate haemophilia?

A
  • in response to trauma
  • anticipation of surgery
59
Q

Why are plasma derived concentrates of factor VIII no longer used? What is the alternative ?

A
  • infection with hepatitis C and HIV occurred
  • recombinant factor VIII now available (no virus contamination)
60
Q

Prolonged clotting time and APTT in haemophilia can be corrected by …

A

fresh plasma
NOT fresh serum

61
Q

What is the effect of haemphilia on PT, TT, platelet count and bleeding time?

A

usually normal

62
Q

Give examples of blood derivatives used to treat patients with coagulation defects

A
  • fresh frozen plasma with all important factos
  • fresh whole blood platelet concentrates
  • factor VIII concentrates
63
Q

What is PPSB?

A

this is the name of the blood product in which vitamin K-dependent coagulating factors are concentrated

64
Q

What factors are contained in PPSB?

A
  • II- prothrombin
  • VII- prokonvertin
  • IX- antihaemophilic factor B
  • X- Stuart Prower factor
  • Prothrombinex (II, IX)
  • fibronogen
65
Q

Give examples of materials that can be used to reduce or stop bleeding in dentistry

A
  • surgicel
  • gelfoam
  • thrombostat
  • kaltostat
  • ferric/calcium sulphate
  • tranexamic acid
  • collaplug
  • amicar
66
Q

What is surgicel?

A

oxidised cellulose; provides framework for clot formation

67
Q

What is gelfoam
?

A

absorbent gelatine sponge- stimulates intrinsic clotting pathway

68
Q

What is thrombostat?

A

topical thrombin

69
Q

What is kaltostat?

A

calcium alginate

releases calcium and aids haeomstasis
calcium is a cofactor in haemostasis !

70
Q

How does calcium/ferric sulphate aid haemostasis?

A

blocks the vascular channels in multiple small bony bleeding points

71
Q

What is collaplug?

A

collagen- acts as a mechanical tamponade, stimulates platelet adhesion and aggregation ,activated factor VIII and releases serotonin (vasoconstriction)

72
Q

What is Amicar?

A

epsilon- amino caproic acid

Minor Oral Surgery (36 decks)

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