Hematology - Hemostasis 1 Flashcards Preview

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Flashcards in Hematology - Hemostasis 1 Deck (57)
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1

What are the stages of hemostasis?

Primary, secondary, and tertiary hemostasis

2

What occurs during primary hemostasis?

The formation of the platelet plug

3

What is primary hemostasis sufficient for?

small vessel injury

4

What occurs during secondary hemostasis?

The formation of the fibrin clot through the coagulation cascade

5

What is secondary hemostasis needed for?

medium/large vessel injury

6

What occurs during tertiary hemostasis?

Fibrinolysis to re-establish blood flow through vessels

7

What clinical signs are associated with primary hemostatic defects?

Mucosal surface bleeding: petechiae, ecchymoses, epistaxis, hemoptysis, hematuria, hematemesis, melena, hematochezia, ocular bleeding, and CNS bleeding

8

What are the key cellular players in primary hemostasis?

endothelial cells and platelets

9

What are the key protein adhesive agents in primary hemostasis?

Von Willebrand factor (vWF), collagen, and fibrinogen

10

What are the key protein agonist agents in primary hemostasis?

ADP, thromboxane A2 (TXA2), and thrombin

11

What prevents platelet adhesion in the normal vessel?

Negatively charged endothelium, NO, prostacyclin, and ADPase

12

When subendothelium is exposed, what occurs during primary hemostasis?

von Willebrand facort binds to the subendothelium, a platelet enzyme binds to the subendothelial vWF, and the aggregation receptor becomes activated. Then another receptor binds to fibrinogen and in simple terms, more platelets are recruited and aggregate.

13

How do activated platelets set stage for secondary hemostasis?

Activated platelets flip their membranes which exposes phosphatidylserine and then provide a docking site for clotting factors needed in secondary hemostasis

14

Generally, what can go wrong with primary hemostasis?

Low platelet number, impaired platelet function, deficient vWF number, impaired vWF function

15

What is the most common acquired disorder of primary hemostasis?

thrombocytopenia

16

What can cause thrombocytopenia?

Use, destruction, and decreased production

17

What inherited disorder can lead to thrombocytopenia?

Congenital macrothrombocytopenia

18

What breeds is congenital macrothrombocytopenia common in?

Cavalier King Charles Spaniels, Norfold Terriers, and others

19

What occurs in congenital macrothrombocytopenia?

The patients don’t bleed because their platelets are too big

20

What are common acuired causes of thrombocytopenia?

Immune-mediated, infectious disease, DIC, and drugs

21

What is thrombopathia?

platelet dysfunction

22

What are the forms of thrombopathia?

inherited and acquired

23

What are the acquired causes of thrombopathia?

DIC, renal and liver disease, and drugs

24

What is the most common inherited primary hemostatic disorder?

von Willebrand's disease

25

What breeds is vWD most common in?

Dobermans, German shorthaired pointers, scottish terriers, and many others

26

If you suspect a hemostatic defect, what testing should be done?

Platelet count and coagulation profile

27

How do you estimate the platelet count from a blood smear?

count in a 100x field - 1 per field equals 20,000 platelets/ul

28

At what platelet count will spontaneous bleeding occur?

Less than 30,000

29

How do you do vWD testing?

With vWF:Ag testing

30

When should you perform vWD testing?

If the patient is of a predisposed breed, young, and previous bleeding

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