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Hematology > Evaluation of Coagulation and Hemostasis > Flashcards

Evaluation of Coagulation and Hemostasis Flashcards

1
Q

What is hemostasis

A

Maintaining blood in its fluid state while stopping bleeding in case of trauma

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2
Q

What is hemostasis

A

Maintaining blood in its fluid state while stopping bleeding in case of trauma

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3
Q

What is primary hemostasis

A

A platelet plug

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4
Q

What is secondary hemostasis

A

Fibrin clot

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5
Q

What is Tertiary hemostasis

A

Breakdown of clot

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6
Q

What is the vascular response to injury

A

There is contraction and narrowing of the lumen of the vessel, which decreases the rate of blood loss and creates a turbulence in which platelets may begin to attach
Loss of endothelium exposes basement membrane (collagen) + releases vWF
Healthy endothelium inhibits platelet activation

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7
Q

Describe primary hemostasis

A

Formation of the temporary platelet plug
Normally Platelets are exposed only to the linings of the blood vessels (endothelium) and heart (endocardium)
blood vessel injury,  platelets are exposed to the subendothelial basement membrane ( collagen)
Damaged endothelium secretes vWF

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8
Q

Describe platelet activation

A

exposure activates the platelets to alter surface membrane properties (become “sticky”) and to adhere to the vessel wall and each other

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9
Q

What products are released when platelets activate

A

ADP (adenosine diphosphate )
Serotonin and histamine vasoconstriction
PF 3coagulation cascade

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10
Q

What is purpura

A

superficial bleeding of skin or mucous membranes

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11
Q

What is petechiae

A
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12
Q

What is ecchymoses

A

larger, small arteriole/venule bleeding

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13
Q

What is superficial bleeding

A

bleeding from mucous membranes (eg epistaxis, hematuria, melena, etc)

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14
Q

What is Von Willebrand factor

A

vWF helps to make the platelets stick to each other and to form the platelet plug,
It is a protein produced by endothelial cells

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15
Q

What does the Von Willebrand factor cause

A

Platelet adhesion to collagen
Platelet–platelet binding or aggregation
vWF helps to activate factor VIII

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16
Q

What is Von Willebrand’s disease

A

most common hemostatic defect in dogs,
Von Willebrand’s factor, is not a clotting factor defect but a protein necessary for the platelets to adhere to the endothelium,
Its absence markedly slows or prevents the formation of a clot - vWF is also cofactor for factor VIII ( hemophilia factor)

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17
Q

What is Von Willebrand

A

It is a protein complex made up of 3 separate proteins

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18
Q

What is type 1 vWF problem

A

Type 1- has low amounts of vWF

Doberman Pinscher, the Shetland Sheepdog, the German Shepherd Dog, and the Standard Poodle

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19
Q

What is type 2 vWF problem

A

Type 2- is missing one of the 3 proteins

German Short-Haired and German Wire-Haired Pointers

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20
Q

What is type 3 vWF problem

A

Type 3- completely missing vWF factor

Most severe form

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21
Q

How do you treat vWF

A

Blood product called cryoprecipitate
Can give FRESH Frozen Plasma

hormone called DDAVP (or desmopressin acetate)

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22
Q

What does the DDAVP hormone do when given

A

It causes sudden release of von Willebrand’s factor into the bloodstream. After a 30-minute onset period, the use of DDAVP shortens the bleeding time for approximately 2 hours after the injection.

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23
Q

Thrombocytopenia

A

a decrease in platelet number

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24
Q

Thrombocytopathia

A

a decrease in platelet function

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25
Q

How do you count platelets

A

Impedance analysers
Clumped platelets may be read as WBC
Cat platelets are very large and clump easily

ALWAYS DO A SMEAR EVALUATION
Should have 10-20 per 40x Field other wise look for clumped platelets

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26
Q

What is the blood mucosal bleeding time

A

Blood that wells up from the incision is blotted with filter paper applied near (but not touching!!) the incision.
A stopwatch is started when the incision is made and stopped when a crescent of blood no longer develops on the filter paper.

Normal BMBT dogs is

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27
Q

What does a BMBT test show

A

platelets (number and function), vessel wall defects (rare) and vWf.

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28
Q

What does a prolonged BMBT show

A

inherited diseases, including vWD
thrombopathia (uremia and aspirin therapy).
thrombocytopenia (probably

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29
Q

In what 2 settings are BMBT used

A

1- As an in vivo pre surgical screening test for vWD, especially in Dobermans,
Pre Treatment for vWF:
vWF supplementation with fresh or fresh frozen plasma or cryoprecipitate. ( 4 hours)
Injection of Desmopressin –DDAVP ( lasts for 2 hours)

2- As a screening test to identify defects in platelet function (thrombopathia) that cannot be detected with routine hemostatic assays.

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30
Q

What is the capillary bleeding time

A

Done on lateral shaved ,shaved surface of front toe with sphygmomanometer cuff on at a pressure of 60 mm hg
The skin is cut twice with a lancet
Bleeding should stop in 1 – 2.5 minutes

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31
Q

What is the intrinsic pathway

A

intrinsic pathway consists of factors present within the blood stream that can be activated without tissue contact

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32
Q

What is the extrinsic pathway

A

extrinsic pathway is activated by contact with cells and tissue fluid outside the vessel. Tissue thromboplastin

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33
Q

What is the common pathway

A

common pathway – results in formation of the fibrin clot

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34
Q

What does the extrinsic pathway provide

A

EXTRINSIC PATHWAY factor VII + tissue damage

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35
Q

What does the extrinsic pathway provide

A

EXTRINSIC PATHWAY factor VII + tissue damage

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36
Q

What is primary hemostasis

A

A platelet plug

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37
Q

What is secondary hemostasis

A

Fibrin clot

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38
Q

What is Tertiary hemostasis

A

Breakdown of clot

39
Q

What is the vascular response to injury

A

There is contraction and narrowing of the lumen of the vessel, which decreases the rate of blood loss and creates a turbulence in which platelets may begin to attach
Loss of endothelium exposes basement membrane (collagen) + releases vWF
Healthy endothelium inhibits platelet activation

40
Q

Describe primary hemostasis

A

Formation of the temporary platelet plug
Normally Platelets are exposed only to the linings of the blood vessels (endothelium) and heart (endocardium)
blood vessel injury,  platelets are exposed to the subendothelial basement membrane ( collagen)
Damaged endothelium secretes vWF

41
Q

Describe platelet activation

A

exposure activates the platelets to alter surface membrane properties (become “sticky”) and to adhere to the vessel wall and each other

42
Q

What products are released when platelets activate

A

ADP (adenosine diphosphate )
Serotonin and histamine vasoconstriction
PF 3coagulation cascade

43
Q

What is purpura

A

superficial bleeding of skin or mucous membranes

44
Q

What is petechiae

A
45
Q

What is ecchymoses

A

larger, small arteriole/venule bleeding

46
Q

What is superficial bleeding

A

bleeding from mucous membranes (eg epistaxis, hematuria, melena, etc)

47
Q

What is Von Willebrand factor

A

vWF helps to make the platelets stick to each other and to form the platelet plug,
It is a protein produced by endothelial cells

48
Q

What does the Von Willebrand factor cause

A

Platelet adhesion to collagen
Platelet–platelet binding or aggregation
vWF helps to activate factor VIII

49
Q

What is Von Willebrand’s disease

A

most common hemostatic defect in dogs,
Von Willebrand’s factor, is not a clotting factor defect but a protein necessary for the platelets to adhere to the endothelium,
Its absence markedly slows or prevents the formation of a clot - vWF is also cofactor for factor VIII ( hemophilia factor)

50
Q

What is Von Willebrand

A

It is a protein complex made up of 3 separate proteins

51
Q

What is type 1 vWF problem

A

Type 1- has low amounts of vWF

Doberman Pinscher, the Shetland Sheepdog, the German Shepherd Dog, and the Standard Poodle

52
Q

What is type 2 vWF problem

A

Type 2- is missing one of the 3 proteins

German Short-Haired and German Wire-Haired Pointers

53
Q

What is type 3 vWF problem

A

Type 3- completely missing vWF factor

Most severe form

54
Q

How do you treat vWF

A

Blood product called cryoprecipitate
Can give FRESH Frozen Plasma

hormone called DDAVP (or desmopressin acetate)

55
Q

What does the DDAVP hormone do when given

A

It causes sudden release of von Willebrand’s factor into the bloodstream. After a 30-minute onset period, the use of DDAVP shortens the bleeding time for approximately 2 hours after the injection.

56
Q

Thrombocytopenia

A

a decrease in platelet number

57
Q

Thrombocytopathia

A

a decrease in platelet function

58
Q

How do you count platelets

A

Impedance analysers
Clumped platelets may be read as WBC
Cat platelets are very large and clump easily

ALWAYS DO A SMEAR EVALUATION
Should have 10-20 per 40x Field other wise look for clumped platelets

59
Q

What is the blood mucosal bleeding time

A

Blood that wells up from the incision is blotted with filter paper applied near (but not touching!!) the incision.
A stopwatch is started when the incision is made and stopped when a crescent of blood no longer develops on the filter paper.

Normal BMBT dogs is

60
Q

What does a BMBT test show

A

platelets (number and function), vessel wall defects (rare) and vWf.

61
Q

What does a prolonged BMBT show

A

inherited diseases, including vWD
thrombopathia (uremia and aspirin therapy).
thrombocytopenia (probably

62
Q

In what 2 settings are BMBT used

A

1- As an in vivo pre surgical screening test for vWD, especially in Dobermans,
Pre Treatment for vWF:
vWF supplementation with fresh or fresh frozen plasma or cryoprecipitate. ( 4 hours)
Injection of Desmopressin –DDAVP ( lasts for 2 hours)

2- As a screening test to identify defects in platelet function (thrombopathia) that cannot be detected with routine hemostatic assays.

63
Q

What is the capillary bleeding time

A

Done on lateral shaved ,shaved surface of front toe with sphygmomanometer cuff on at a pressure of 60 mm hg
The skin is cut twice with a lancet
Bleeding should stop in 1 – 2.5 minutes

64
Q

What is the intrinsic pathway

A

intrinsic pathway consists of factors present within the blood stream that can be activated without tissue contact

65
Q

What is the extrinsic pathway

A

extrinsic pathway is activated by contact with cells and tissue fluid outside the vessel. Tissue thromboplastin

66
Q

What is the common pathway

A

common pathway – results in formation of the fibrin clot

67
Q

What does the intrinsic pathway provide

A

the intrinsic pathway; factors XII, XI, IX, and VIII are components of the intrinsic system.
- mnemonic -it is not $12, but $11.98” (for factors XII, XI, IX, and VIII).

68
Q

What does the extrinsic pathway provide

A

EXTRINSIC PATHWAY factor VII + tissue damage

69
Q

What are the Vitamin K dependant clotting factors

A

FII, FVII, FIX, FX

Clotting proteins produced by the liver

Require Vit K to be activated

70
Q

What is deep bleeding

A

formation of large hematomas or bleeding into body cavities

Large Hematomas
Hemothorax
hemoperotoneum

71
Q

What happens with a mixed hemostatic defect

A

Dogs and cats with mixed hemostatic defects (primary plus secondary) develop a combination of petechiae, ecchymoses, mucosal bleeding, hematomas, and intracavitary bleeding. Mixed hemostatic defects are almost exclusively associated with DIC, and are common in dogs and cats

72
Q

What is DIC

A

disseminated intravascular coagulopathy

Sometimes called a consumptive coagulopathy

73
Q

When does DIC occur

A

DIC does not occur by itself but as a complicating factor from another underlying condition or critical illness.

74
Q

What are the clinical signs of DIC

A

Prolonged PT
Prolonged APTT
Increased FDP or D-dimers
Decreased platelets

75
Q

How do you sample for coagulation tests

A

Clean venipuncture is essential. Poor venipuncture will result in activation of coagulation due to contamination with tissue factor
if the vein is not entered on the first attempt, a fresh needle should be used.
vacutainer collection is preferred
Blue citrate tube
Plastic tube, not glass

76
Q

What is the ACT test used for

A

evaluation of the intrinsic and common pathways
Clotting Factors must be decreased by 95%
Whole blood without anticoagulant is added to a special tube containing diatomaceous earth
tube should be incubated at 37 C
ACT relies on the patient’s platelets for provision of phospholipid to support the reaction – but is not overly prolonged with thrombocytopathias

77
Q

How do you do a ACT test

A

evaluation of the intrinsic and common pathways
Clotting Factors must be decreased by 95%
Whole blood without anticoagulant is added to a special tube containing diatomaceous earth
tube should be incubated at 37 C
ACT relies on the patient’s platelets for provision of phospholipid to support the reaction – but is not overly prolonged with thrombocytopathias

78
Q

What % does a carrier of hemophilia have

A

A carrier may only have a 40 – 60 % decrease in factor VIII or IX
Bleeding problems occur when you have less than 5% of the factor

79
Q

What is hemophilia A

A

Factor VIII deficiency

80
Q

What is hemophilia B

A

Christmas disease; Factor X hemophilia

81
Q

How do you get hemophilia

A

Sex linked
No breed predisposition
Quite rare

82
Q

What is the normal ACT in dogs

A

Normal ACT for dogs is 60 - 90 seconds

Due to reliance on endogenous platelets for the reaction, platelet counts of

83
Q

What is the normal ACT in cats

A

For cats is 45 - 160 seconds.

84
Q

What causes a prolonged ACT

A

liver disease,
congenital coagulopathies ( hemophilia A and B),
vitamin K-responsive coagulopathies (FII, FVII, FIX, FX)

DIC,

85
Q

What is the aPTT associated with

A

intrinsic and common pathways like ACT
Collect in blue top tube ( citrate)
Add a contact surface activator of the intrinsic system + Calcium
It will not be affected by low platelets

86
Q

What is PT associated with

A

Extrinsic( VII) and common pathway factors.
Tissue thromboplastin (a source of tissue factor) and calcium are added to the patient plasma and the time for clot formation is recorded. N= 7-10 sec
sensitive indicator of poisoning with anticoagulant rodenticides ( warfarin)
factor VII is the vitamin K-dependent factor with the shortest half-life (approximately 6 hours in the dog), the PT may be prolonged within 24 hours following rodenticide ingestion

87
Q

What is PIVKA

A

Proteins induced by Vitamin K Absence

88
Q

Describe PIVKA

A

vitamin K-dependent coagulation factors (FII, FVII, FIX, FX) are produced in the liver as nonfunctional precursors
precursors are activated, in the presence of vitamin K,
absence of vitamin K, there is an increase in these precursors
Can detect rodenticide poisoning earlier than 6 hours

89
Q

What are the Misc tests for coagulation

A

Clot retraction

Whole blood clotting time

90
Q

What is fibrinogen

A

Fibrinogen is an acute phase reactant protein and elevated values are seen in inflammation and renal disease

91
Q

How do you calculate fibrinogen

A

Heat precipitation:
2 edta microhematocrit tube
second tube is heated at 56 C for 3 minutes to casuse the firinogen to become fibrin
Spin and measure the protein
The difference between the 2 is the fibrinogen

92
Q

What is Fibrolysis

A

Plasminogen, a proenzyme, is activated by F XIIa to Plasmin
Plasmin biodegrades fibrinogen and fibrin, generating fibrin degradation products (FDPs)
FDPs also exert a profound inhibitory effect on platelet function
contributing to the petechiae and ecchymoses in patients with disseminated intravascular coagulation (DIC)

93
Q

how do you test for tertiary hemostasis

A

check for Fibrinogen degradation products-FDP

94
Q

Describe DIC

A

Prolonged PT
Prolonged APTT
Increased FDP or D-dimers
Decreased platelets

Hematology (15 decks)

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