Coagulation Screen

Question 1

Indications for performing a coagulation screen?

Answer 1

1. confirm suspected coagulopathy
2. monitor coagulation status of patient on anti-coagulants
3. assess coagulation pre-surgery
4. assess synthetic liver function

Question 2

What activates the intrinsic clotting pathway?

Answer 2

Contact with a damaged surface

Question 3

What activates the extrinsic clotting pathway?

Answer 3

The release of tissue factors

Question 4

What is prothrombin time (PT)?

Answer 4

• Measure of time taken for blood to clot via EXTRINSIC pathway
• INR is standardised version of this
• Measure of overall clotting factor synthesis or consumption

Question 5

What conditions can affect prothrombin time (PT)?

Answer 5

• liver disease
• disseminated intravascular coogulation
• vitamin K deficiency
• warfarin levels

Question 6

What is activated partial thrombopalstin time (APTT)?

Answer 6

• measure of time taken for blood to clot via INTRINSIC pathway
• measure of overall clotting factor synthesis or consumption
• also indicates issues with factors VIII, vWF, IX, XI

Question 7

Which conditions can increase bleeding time (finger prick)?

Answer 7

• von Willebrans disease (autosomal dominant)
• Benrard-Soulier syndrome
• TTP/ITP/HUS/DIC
• thrombocytopenia

Bleeding time measures formation of platelet plug.

Question 8

What conditions can affect APTT?

Answer 8

• haemophilia A (VIII, x-linked recessive)
• haemophilia B (IX, x-linked recessive)
• haemophilia C (XI - autosomal recessive)
• von Willebrands disease

Question 9

What type of disorder causes increased bleeding time (from finger prick test)?

Answer 9

Platelet specific disorders

Question 10

What is thrombin time?

Answer 10

• Test of how fast fibrinogen is converted to fibrin by thombin.
• if prolonged, indicates sythetic issue or consumption issue

Question 11

Vitamin K deficiency/Warfarin use:

• PT/INR
• APTT
• Bleeding time
• Platelet count

Answer 11

• PT/INR - raised
• APTT - raised
• BT - normal
• platelets - normal

BT: bleeding time (finger prick)

Question 12

Haemophilia A/B/C:

• PT/INR
• APTT
• Bleeding time
• platelet count

Answer 12

• PT/INR - normal
• APTT - raised
• BT - normal
• platelets - normal

Question 13

von Willebrand’s disease:

• PT/INR
• APTT
• Bleeding time
• Platelet count

Answer 13

• PT/INR - normal
• APTT - normal/raised
• BT - raised
• platelets - normal

Question 14

Disseminated intravascular coagulation (DIC):

• PT/INR
• APTT
• Bleeding time
• Platelet count

Answer 14

• PT/INR - raised
• APTT - raised
• BT - raised
• Platelets - low

Question 15

ITP/TTP/HUS

• PT/INR
• APTT
• Bleeding time
• Platelet count

Immune thrombocytopenic purpura (ITP)
Thrombotic thrombocytopenic purpura (TTP)
Haemolytic uraemic syndrome (HUS)

Answer 15

• PT/INR - normal
• APTT - normal
• BT - raised
• platelets - low

Question 16

Symptoms of clotting disorders

Answer 16

• haemorthrosis
• muscle haematomas
• prolonged bleeding after dental surgery

Question 17

Symptoms of platelet disorders

Answer 17

• petechiae
• bruising
• contact bleeding (e.g. gums)
• menorrhagia