Week 10: Bleeding and Clotting disorders

Question 1

Which are the intrinsic pathway clotting factors

Answer 1

8, 9, 11, 12

Question 2

Which are the extrinsic pathway clotting factors

Answer 2

7

Question 3

Which are the Vit K dependent clotting factors

Answer 3

2, 7, 9, 10

Question 4

Does APTT assess the intrinsic or extrinsic pathway

Answer 4

APTT = intrinsic

Question 5

Does PT assess the intrinsic or extrinsic pathway

Answer 5

PT = extrinsic

Question 6

What is the purpose of a blood mixing study?

What products are mixed?

Answer 6

To determine the cause of a long APTT

APTT is mixed with normal plasma

Question 7

When APTT is mixed with normal plasma (mixing study), APTT time CORRECTS.

What condition does this show?

Answer 7

Clotting factor deficiency

Question 8

When APTT is mixed with normal plasma (mixing study), APTT time DOES NOT CORRECT.

What condition does this show?

Answer 8

Clotting factor inhibitor

eg lupus anticoagulant

Question 9

Which factor is deficient in haemophilia A

Answer 9

Factor 8

Question 10

Which factor is deficient in haemophilia B

Answer 10

Factor 9

Question 11

Inheritance of haemophilia

Answer 11

X-linked

Question 12

Inheritance of Von Willebrand’s disease

Answer 12

Autosomal dominant

Question 13

Function of Von Willebrand factor

Answer 13

• Binds to and stabilises factor 8 (prevents it from being proteolysed)
• Binds platelets to sub-endothelium

Question 14

Desmopressin (DDAVP) is used in treatment of Von Willebrand’s disease. What is its mechanism of action?

Answer 14

Desmopressin causes release of VwF stored in the endothelium

Question 15

Precipitating events for DIC

Answer 15

1. Sepsis
2. Trauma, major bleed
3. Cancer
4. Incompatible blood transfusion
5. Liver disease
6. Obstetric catastrophe eg placental abruption, pre-eclampsia

Question 16

In DIC, how are the following blood tests changed

• APTT
• PT
• platelets
• fibrin
• d-dimer

Answer 16

APTT: increased
PT: increased
Platelets: decreased
Fibrin: decreased
D-dimer: increased

Question 17

Complications of DIC

Answer 17

Organ failure

-due to tissue ischaemia from intravascular fibrin deposition

Question 18

Risk factors for developing VTE

Answer 18

• Age
• Immobilisation
• Surgery
• Air travel
• Cancer
• Pregnancy
• OCP, HRT
• Anti-phospholipid antibodies
• Thrombophilia

Question 19

Which are the naturally occurring anticoagulants

Answer 19

1. Protein C
2. Protein S
3. Antithrombin

Question 20

Describe the pathophysiology of Factor V Leiden disease

Answer 20

Point mutation in Factor 5 gene at APC cleavage site.

Anticoagulant cannot link efficiently onto 5a to inactivate it -> slow inactivation

Question 21

Which anticoagulant inactivates Factor 5

Answer 21

Protein C

Question 22

Which anticoagulant drugs have a rapid onset

Answer 22

• Heparin
• Apixaban
• Dagibatran

Question 23

Which anticoagulant drugs have a slow onset

Answer 23

Warfarin

Question 24

What INR level tends to be associated with intracerebral haemorrhage

Answer 24

INR 2-3.5

Question 25

What exactly is D-dimer

Answer 25

A product of fibrin breakdown (clotting destruction)

Question 26

Significance of PT and APTT

Answer 26

Measures how long blood takes to clot.

PT and APTT would thus be HIGH in bleeding disorders

Question 27

Causes of increased vWF factor levels

Answer 27

ACUTE PHASE PROTEIN
so rises in

• stress
• cancer
• thyrotoxicosis
• oestrogens, pregnancy

Question 28

Which bleeding disorders result in a palpable bruise

Answer 28

• Haemophilia (A and B)

- HSP

Question 29

Is pregnancy a pro-thrombotic or pro-bleeding state

Answer 29

Pro-thrombotic (to prevent post partum bleeding)