Bleeding and coagulation

Question 1

What is haemostasis?

Answer 1

The arrest of bleeding and maintenance of vascular patency

Question 2

What is primary and secondary haemostasis?

Answer 2

Primary haemostasis is the formation of a platelet plug

Secondary haemostasis is the formation of a fibrin clot

Question 3

Where are platelets formed?

Answer 3

Platelets are formed in the bone marrow by budding from megarokaryocytes

Question 4

What is the life span of a platelet?

Answer 4

7-10 days

Question 5

What are some of the possible causes of failure of platelet plug formation?

Answer 5

Vascular causes
E.g reduced collagen in blood vessels in elderly patients and inherited causes such as marfan’s

Thrombocytopenia due to anti-platelet medications and NSAIDs

Von Willebrand disease

Lack of vitamin C e.g scurvy

Question 6

Which is generally more severe, failure of primary haemostasis or failure of secondary haemostasis?

Answer 6

Failure of secondary haemostasis

Question 7

How does failure of platelet plug formation present?

Answer 7

Spontaneous bruising and purpura (usually in the lower limbs due to gravity)

Mucosal bleeding (epistaxis, GI, conjunctival and menorrhagia)

Intracerebral bleeds in severe cases

Question 8

What is the screening test for primary haemostasis?

Answer 8

Platelet count

Question 9

What are the screening tests for secondary haemostasis?

Answer 9

Prothrombin time

Activated partial thromboplastin time

Question 10

What are some of the naturally occurring anticoagulants?

Answer 10

Anti-thrombin

Protein C and S

Question 11

Does prothrombin time test the extrinsic or the intrinsic pathway?

Answer 11

Extrinsic pathway

It measures the propagation side of fibrin clot formation

Question 12

What is the normal range for prothrombin time?

Answer 12

12-13 seconds

Question 13

What are some of the causes of a prolonged PT?

Answer 13

Warfarin therapy

DIC

Liver disease

Vitamin K deficiency (premature babies and ITU patients)

Question 14

Does the APTT test the extrinsic or the intrinsic pathway?

Answer 14

Intrinsic pathway

Measure the amplification side of fibrin clot formation

Question 15

What is the normal range for APTT?

Answer 15

30-40 seconds

Question 16

What are some of the possible causes of prolonged APTT?

Answer 16

Heparin therapy

Haemophilia

VW disease

Antiphospholipid syndrome

Question 17

Thrombocytopenia is the most common cause of primary haemostatic failure. What are some of the possible cause of thrombocytopenia?

Answer 17

Cancer

DIC

Immune thrombocytopenic purpura

Question 18

What is immune thrombocytopenic purpura?

Answer 18

An autoimmune cause of thrombocytopenia which involves antibodies against platelets

Question 19

how is immune thrombocytopenic purpura managed?

Answer 19

Prednisolone (steroids)

Question 20

VWF deficiency can be acquired or hereditary. Which is more common?

Answer 20

Mostly hereditary

Question 21

What mode of inheritance does VWF disease involve?

Answer 21

Autosomal dominant

Question 22

VWF affects men and women equally, so why are men less likely to be diagnosed?

Answer 22

Women are more likely to present as they may have the symptom of menorrhagia

The condition may not become apparent in men until they have an accident or operation and notice abnormal bleeding

Question 23

Is haemophilia due to a single or multiple clotting factor deficiencies?

Answer 23

Single clotting factor deficiency

Question 24

Where are coagulation factors synthesised?

Answer 24

In hepatocytes in the liver

Question 25

What happens to coagulation factors in liver failure?

Answer 25

Coagulation factors are reduced

Question 26

What are the four clotting factors?

Answer 26

II, VII, IX and X | 2,7,9 and 10

Question 27

Where is vitamin K absorbed? What does it require for absorption?

Answer 27

Vitamin K is absorbed in the upper intestine Requires bile salts for absorption

Question 28

What are some of the possible causes of vitamin K deficiency?

Answer 28

Warfarin Diet/ malabsorption ``` Obstructive jaundice (e.g pancreatic cancer) ``` Haemorrhagic disease of the newborn

Question 29

Why does DIC occur?

Answer 29

All the clotting factors are used up in thrombus formation

Question 30

What are some of the possible causes of DIC?

Answer 30

Sepsis Obstetric emergencies Malignancy Hypovolaemic shock (hypoxia causes tissue damage)

Question 31

How is DIC managed?

Answer 31

Treat the underlying cause (e.g antibiotics or removing the placenta) Platelets and plasma transfusions and fibrinogen replacement

Question 32

What mode of inheritance does haemophilia involve?

Answer 32

X-linked inheritance | only affects males

Question 33

Where are the most common sited of bleeding in haemophilia?

Answer 33

Ankle, knee and elbow joints These sites take a lot of strain and get a lot of bumps

Question 34

Is haemophilia A or B more common?

Answer 34

Haemophilia A is most common

Question 35

Which coagulation factor deficiencies do haemophilia A and B involve?

Answer 35

Haemophilia A - factor VIII deficiency Haemophilia B - factor IX deficiency

Question 36

What are some of the clinical features of haemophilia?

Answer 36

Recurrent haemarthroses (blood in the joint – very painful and limits movement Recurrent soft tissue bleeds (e.g bruising in toddlers) Tend to bleed into big muscles e.g iliopsoas Prolonged bleeding after dental extractions, surgery and invasive procedures

Question 37

How is haemophilia managed?

Answer 37

Infusions of factor VIII Joint replacements

Question 38

Which class of drugs are arterial Vs venous thrombotic events treated with?

Answer 38

Arterial - anti-platelets Venous - anti-coagulants

Question 39

Is venous thrombosis a problem of primary or secondary haemostasis?

Answer 39

Problem of secondary haemostasis - involves the formation of a fibrin clot

Question 40

What are the components for Virchow's Triad?

Answer 40

Stasis vessel wall (valve problems) Hypercoagulability

Question 41

What is the strongest risk factor for venous thromboembolism?

Answer 41

Having had a previous DVT or PE

Question 42

What is thrombophilia?

Answer 42

Familial or acquired disorders which predispose to thrombosis

Question 43

Give some examples of hereditary thrombophilias

Answer 43

Factor V Leiden Antithrombin deficiency Protein C or S deficiency

Question 44

What are the indications for screening for thrombophilia?

Answer 44

Venous thrombosis at <45 years old Recurrent or unusual venous thrombosis FH of venous thrombosis or thrombophilia

Question 45

What are the components of antiphospholipid antibody syndrome?

Answer 45

Recurrent thromboses Recurrent miscarriage Mild thrombocytopenia

Question 46

How is antiphospholipid syndrome managed?

Answer 46

Aspirin / Warfarin (can get venous or arterial thrombosis) *Heparin should be used in pregnancy

Question 47

Is arterial thrombosis a problem of primary or secondary haemostasis?

Answer 47

Arterial thrombosis is a problem of primary haemostasis - involves the formation of a platelet rich thrombus

Question 48

How do platelets bind to sub endothelial collagen? | platelet adhesion

Answer 48

Via glycoprotein 1b and VWF

Question 49

How doe platelets attach to eachother? | platelet aggregation

Answer 49

Via GPIIbIIIa and fibrinogen

Question 50

An isolated prolonged partial thromboplastin time selects a deficiency of factors in which pathway?

Answer 50

The intrinsic pathway

Question 51

Factor VIII deficiency is a deficiency in which pathway?

Answer 51

The intrinsic pathway

Question 52

An isolated prolonged prothrombin time reflects a deficiency of factors involved in which pathway?

Answer 52

The extrinsic pathway

Question 53

Deficiencies in common pathway factors cause a prolongation of both the prothrombin time and the activated partial thromboplastin time. Which clotting factors are involved in the common pathway?

Answer 53

II, V and X

Question 54

Factor VII deficiency is a deficiency in which pathway?

Answer 54

The extrinsic pathway