hemostasis

Question 1

What are the steps of hemostasis?

Answer 1

primary hemostasis
secondary hemostasis
fibrinolysis

Question 2

What are the phases that occur during primary hemostasis?

Answer 2

PHASE I
- vasoconstriction: decrease in local blood flow

PHASE II
- platelet plug (Vin Willebrand factor): thromboplastin -> adherence of platelets to sub-endothelial tissue

PHASE III

• tamponade: surrounding tissue tension acts as a tamponade for bleeding
• interstitial hemorrhage is less profuse than external or internal hemorrhage

Question 3

When is vasoconstriction less effective?

Answer 3

• in partially injured vessels
• in stiff atherosclerotic vessels
• in large veins (poor muscle coat)

Question 4

What occurs during secondary hemostasis?

Answer 4

ACTIVATION OF COAGULATION CASCADE

- includes the intrinsic & extrinsic pathways

Question 5

What are the factors activated in the intrinsic pathways & what test is used to measure their function?

Answer 5

factor XII
factor XI
factor IX
factor VIII

PTT

Question 6

Which factor is activated in the extrinsic pathway & what test is used to assess its function?

Answer 6

factor XII

PT

Question 7

What factor is activated in the common pathway?

Answer 7

factor X

which activates the conversion of thrombin to fibrinogen

Question 8

What initiates the extrinsic pathway?

Answer 8

tissue lipoprotein

Question 9

How does fibrinolysis occur?

Answer 9

tissue plasminogen activator converts plasminogen to plasmin which breaks down fibrin

Question 10

What test will be affected incase of deficiency of factors VIII & IX and what is the disease that causes this deficiency?

Answer 10

HEMOPHILIA A for factor VIII & B for factor IX

PTT is affected

Question 11

What are the manifestations of hemophilia?

Answer 11

• spontaneous bleeding in childhood (severe form)

- bleeding after mild trauma or surgery

Question 12

How should hemophilia be treated?

Answer 12

infusion of factor concentrate 1 hour before surgery & 10 days after

Question 13

What are the manifestations of Von Willebrand disease & how should it be treated?

Answer 13

• purpuric eruptions, ecchymosis or bleeding per orfices

- infusion of Von Willebrand factor

Question 14

What are the hemostatic disorders associated with liver disease?

Answer 14

• decreased concentration of factors 1972 (effected by vitamin K)
• thrombocytopenia due to hypersplenism

Question 15

How should hemostatic disorders due to hepatic diseases be treated?

Answer 15

• Vit K administration

- Fresh frozen plasma

Question 16

Vitamin K is a co-factor in the synthesis of which clotting factors?

Answer 16

1972
X, IX, VII, II

increase in traumatic bleeding

Question 17

What are the causes of vit K deficiency?

Answer 17

• inadequate diet or TPN
• obstructive jaundice
• prolonged broad antibiotic
• malabsorption

Question 18

How should vit. K deficiency be treated?

Answer 18

• daily vit. K injection (SLOW IV)

- FFP in emergencies

Question 19

What are the causes of DIC?

Answer 19

• septicemia
• severe shock, trauma, & burns (SIRS)
• ABO incompatible transfusion

Question 20

What occurs during DIC?

Answer 20

• widespread activation of coagulation within circulation leading to dilution of clotting factors

Question 21

How should DIC be treated?

Answer 21

• treat underlying cause
• FFP to replace coagulation factors
• platelet transfusion

Question 22

What are the platelet disorders?

Answer 22

THROMBOCYTOPENIA

THROMBASTHENIA

Question 23

What is the normal platelet count?

Answer 23

150 000 to 400 000

Question 24

What are the causes of thrombocytopenia?

Answer 24

PRIMARY: ITP
SECONDARY: Bone marrow suppression OR increase destruction in hypersplenism

Question 25

What are the causes of thrombasthenia?

Answer 25

disorders of platelet function due to drugs like ASPRIN & NSAIDS

Question 26

How can we differentiate between the 2 secondary causes of thrombocytopenia?

Answer 26

Bone marrow aspiration to search for megakaryocites (platelet precursors) - decreases in megakaryocites -> bone suppression - increase megakaryocites -> hypersplenism

Question 27

What are the characters of bleeding if the defect is of primary hemostasis?

Answer 27

- superficial bleeding (patichae, purpura, & easy bruisability) - early onset following trauma - controlled by local pressure

Question 28

What are the characters of bleeding if the defect is of secondary hemostasis?

Answer 28

- bleeding is deep (hematoma inside muscle) - delayed onset following trauma - local pressure is ineffective

Question 29

What disorder has a decreased number of platelets < 100 000?

Answer 29

thrombocytopenia

Question 30

What is the normal bleeding time & what diseases increase it?

Answer 30

normal = < 8 minutes - thrombocytopenia - abnormal platelet function - deficiency of Von Willbrand disease - Vascular abnormality

Question 31

What is the normal PT time & what factors affect it?

Answer 31

normal = 12 - 15 seconds - deficiency in factor VII or X

Question 32

What is the normal PTT time & what factors affect it?

Answer 32

normal = 30 - 40 seconds - factor XII, XI, X, IX, VIII, V, II

Question 33

What is the normal INR and what effects it?

Answer 33

normal = 1 - patients taking oral anticoagulants (2-3) - patients with prosthesis (2.5-3.5)

Question 34

an increase in FDPs (fibrinogen degradation products) is an indication of?

Answer 34

DVT