Bleeding disorders seen in the dental practice Flashcards
(72 cards)
1
Q
What is the function of both intrinsic and extrinsic coagulation pathways?
A
activation of factor V
2
Q
What is the function of activated factor V (Xa)?
A
cleaves prothrombin to release thrombin
(thrombin catalyses formation of fibrin clot)
3
Q
What is the result of the activation of coagulation inhibitors?
A
restrict coagulation to the site of injury
- prevention of pathological coagulation
4
Q
How can platelet disorders be described?
A
- quantitative
- qualitative
5
Q
Give examples of inherited qualitative/quantitative platelet disorders
A
- bernard soulier disease
- glazmanns thrombasthenia
6
Q
Give examples of acquired platelet disorders
A
- altered platelet function due to aspirin or NSAID intake
7
Q
Outline some clinical presentations of platelet disorders
A
- purpura
- petechiae
- mucosal bleeding
- epistaxis
- menorrhagia
8
Q
What is the difference between purpura and petechiae?
A
- purpura measures between 4-10 mm
- petechiae <4mm
9
Q
Give examples of inherited clotting cascade disorders
A
- haemophilia A and B
- Von williebrands disease
10
Q
Give an examples of acquired clotting cascade disorder
A
- disseminated intravascular coagulation (DIC)
- Liver disease
- vitamin K deficiency
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
12
Q
Spontaneous, plaque-free gingival bleeding could be an early sign of …
A
leukaemia
13
Q
Prothrombin time evaluates …
A
extrinsic pathway
(II, V, VII, X and fibrinogen)
2, 5, 7, 10
14
Q
What are the normal values for prothrombin time ?
A
12-15 seconds
15
Q
Prothrombin time is prolonged in …
A
- warfarin treatment
- liver disease
- vitamin K deficiency
- DIC
vitamin K clotting factors, 2, 7, 9, 10
16
Q
INR evaluates …
A
extrinsic pathway of blood coagulation (II, V, VII, X, fibrinogen)
17
Q
What are the normal values for INR?
A
About 1.0
(0.8-1.2) )
18
Q
INR is prolonged in …
A
- warfarin treatment
- liver disease
- vitamin K deficiency
- DIC
19
Q
APTT (activated partial thromboplastin time) evaluates …
A
intrinsic pathway
which includes factor II, V and X
20
Q
What are the normal values for APTT?
A
25 (+/- 10) seconds
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
22
Q
What does thrombin time evaluate?
A
the abnormality in converting fibrinogen (soluble protein) to fibrin (an insoluble protein)
23
Q
What are the normal thrombin time values?
A
10-15 seconds
24
Q
Thrombin time is prolonged in …
A
- heparin treatment
- DIC
25
What is the function of "bleeding time" ?
assess platelet and normal blood vessel function
26
What is the normal value of bleeding time?
2-9 minutes
27
The value of bleeding time depends on ...
method used (to achieve bleeding?)
Ivy or Duke
28
Bleeding time is prolonged in ...
* platelet disorders
* vessel wall disorders
* fibrinogen disorders
* von willibrands disease
29
How is the INR calculated ?
it is a ratio of the patients PT (prothrombin time) to a normal control
30
What is the advantage of the INR over the PT?
it uses international standards and thus the anti-coagulant control can be compared in different hospitals and clinics around the world
31
What is the normal platelet count ?
150 000- 450 000 platelets per microlitre
32
How are bleeding disorders generally categorised?
* coagulation disorders
* vascular defects
* Platelet defects (number or structural defects)
* fibrinolytic defects
33
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
True
34
What are the functions of von willie brands factor?
* 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
What is the benefit of factor VIII complex formation?
protection from inactivation and clearance
36
What is the most common inherited bleeding disorder?
von williebrands disease
37
What is the pattern of inheritance of von williebrands disease?
autosomal dominant
38
Expression/presentation of von williebrands disease varies. True or false
True
39
What tests are impacted by von williebrands disease ?
* APTT
* Clotting time
* Bleeding time
40
Patients with VWD may suffer from deep seated haemorrhages. What is the cause of this?
factor VIII deficiency
(remember VWF is carrier for factor VIII)
41
What is the impact of VWD on prothrombin time?
remains normal
42
What is the impact of VWD on Thrombin time?
remains normal
43
What is the impact of VWD on platelet count?
remains normal
44
What is the impact of VWD on a factor VIII?
factor VIII assay is usually reduced
45
A tourniquet test for patients with VWD is usually _______.
positive
46
Type 1 VWD is considered to be a ______ defect. What is the pattern of inheritance
quantitative defect
autosomal dominant
47
How is type 1 VWD usually confirmed?
* abnormal platelet function tests
* decrease in VWF antigen
* proportional decreae in factor VIII activity
48
Type II VWD is a ____ defect.
qualitative
49
What are the subtypes of type II VWD? Outline their patterns of inheritance
* A
* B
* M
* N
They are all autosomal dominant
50
What is the pattern of inheritance for type III VWD?
autosomal recessive
very severe but rare
51
What is the most common type of VWD?
Type I
(70% of cases)
52
What is the clinical presentation of VWD?
resembles classic haemophilia
53
What treatment is offered for VWD?
desmopressin which raises VWF levels in mild diseae
raises factor VIII/VWF concentrates in more severe disease
54
Why does an affected male with haemophilia not transmit the disease to his son ?
this is because the Y chromosome does not carry the haemophilic gene
55
A small proportion of female carriers of haemophilia may bleed significantly. True or false
True
56
What are the general clinical presentations of haemophilia?
* bruisinh
* muscle and joint haemorrhages
* prolonged haemorrhage after surgery or trauma (no excessive bleeding after minot cuts)
57
What is the clinical presentation of severe haemophilia?
spontaneous bleeding into large muscles and joints unless regular treatment with factor VIII concentrate is given
58
When is factor VIII administered in mild and moderate haemophilia?
* in response to trauma
* anticipation of surgery
59
Why are plasma derived concentrates of factor VIII no longer used? What is the alternative ?
* infection with hepatitis C and HIV occurred
* recombinant factor VIII now available (no virus contamination)
60
Prolonged clotting time and APTT in haemophilia can be corrected by ...
fresh plasma
NOT fresh serum
61
What is the effect of haemphilia on PT, TT, platelet count and bleeding time?
usually normal
62
Give examples of blood derivatives used to treat patients with coagulation defects
* fresh frozen plasma with all important factos
* fresh whole blood platelet concentrates
* factor VIII concentrates
63
What is PPSB?
this is the name of the blood product in which vitamin K-dependent coagulating factors are concentrated
64
What factors are contained in PPSB?
* II- prothrombin
* VII- prokonvertin
* IX- antihaemophilic factor B
* X- Stuart Prower factor
* Prothrombinex (II, IX)
* fibronogen
65
Give examples of materials that can be used to reduce or stop bleeding in dentistry
* surgicel
* gelfoam
* thrombostat
* kaltostat
* ferric/calcium sulphate
* tranexamic acid
* collaplug
* amicar
66
What is surgicel?
oxidised cellulose; provides framework for clot formation
67
What is gelfoam
?
absorbent gelatine sponge- stimulates intrinsic clotting pathway
68
What is thrombostat?
topical thrombin
69
What is kaltostat?
calcium alginate
releases calcium and aids haeomstasis
calcium is a cofactor in haemostasis !
70
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How does calcium/ferric sulphate aid haemostasis?
blocks the vascular channels in multiple small bony bleeding points
71
What is collaplug?
collagen- acts as a mechanical tamponade, stimulates platelet adhesion and aggregation ,activated factor VIII and releases serotonin (vasoconstriction)
72
What is Amicar?
epsilon- amino caproic acid
