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Flashcards in Haematology Deck (51)
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1

What is APTT?

Activated partial thromboplasmin time

2

What is haemostasis?

Process whereby haemorrhage following vascular injury is arrested
Tightly regulated by vascular endothelium, platelets, coagulation factors and fibrinolysis

3

What is activated in injury of the vascular wall?

Tissue factor-> coagulation cascade
Collagen exposure and vWF-> platelet activation
Vasoconstriction-> stable plug

4

How does the endothelium usually act as an anticoagulant?

Prostacyclin, NO, heparin sulphate

5

What are platelets derived from?

Megakaryocyte shards

6

What stimulates platelet production?

Thrombopoetin

7

How long do platelets circulate for before being destroyed?

6-8 days

8

Describe the extrinsic pathway in the coagulation cascade

Tissue injury-> tissue factor and phospholipids
F7->F7a
F8-> F10->F10A
Prothrombin-> thrombin
Fibrinogen-> fibrin

9

Describe the extrinsic pathway in the coagulation cascade

-ve surface (collagen/plastic)
F12-F12A
F11-F11A
F9->F9A
F10-> F10A
Prothrombin-> Thrombin
Fibrinogen-> Fibrin

10

What initiates fibrinolysis?

Coagulation cascade
tPA (tissue plasminogen activator)
urokinase-like plasminogen activator

11

Plasminogen does what?

Turns into plasmin, degrades factor 5&7
Fibrin-> soluble products

12

What does a blood count and film show?

Number and morphology of platelets
May show leukaemia

13

When is PT (prothrombin time) extended?

Abnormal factor II, V, VII, X
Liver disease
Warfarin
Vitamin K deficiency
DIC

14

What is DIC?

Disseminated intravascular coagulation
Seen in septicaemia and post partum haemorrhage

15

When is APTT prolonged?

Deficiency/inhibition of II, V, VII, IX, X, XI, XII
Unfractionated heparin therapy
Vitamin K deficiency
DIC

16

What is a correction test?

Add normal plasma to patient's plasma so its 50:50
See if clotting time corrects
If it does it is a deficiency not an inhibitor

17

What do you look for in a bleeding disorder examination?

Signs of systemic diseases
Skin, mouth, fundi, joints
Easy bruising?
Purpura, bruising, petechiae

18

What is scurvy?

Vitamin C deficiency

19

What are Henoch-Schönlein purpura?

Small vessel vasculitis
Purple nodules that do not disappear on pressing
Intradermal bleeding
Seen in young males
+glomerulonephritis, joint pain, abdo pain

20

What is haemorrhagic telangiectasia?

Small red/purple clusters if dilated capillaries on skin or surface of organs

21

What is thrombocytopenia?

Low platelet count
Failure of production?
Increased consumption?
Dilutional?
Abnormal distribution?

22

What would cause a failure in the production of platelets?

Selective megakaryocyte depression
Dugs/chemicals/viral infections
Part of generalised bone marrow failure
Leukaemia, lymphoma, cancer
Aplastic anaemia
HIV

23

What would cause an increased consumption of platelets?

Immune/autoimmune
Drug induced (heparin)
Infections
DIC

24

What would cause dilutional thrombocytonpenia?

Massive blood transfusion

25

What do you treat congenital disorders if platelet function with?

Tranexamic acid, platelet transfusion
Avoid antiplatelet drugs

26

Give 2 examples of congenital disorders of platelet function

Bernard-Soulier
Glanzmann's

27

What would cause an acquired disorder of platelet function?

Antiplatelet agents (aspirin, NSAIDs)
Renal failure
Gammaglobulins
Cardiopulmonary bypass
Myeloproliferative disorders

28

Name 4 congenital coagulation disorders

Haemophilia A, Hameophilia B, vWF disease, Factor XI deficiency

29

What is tranexamic acid?

Blocks fibrinolysis
Used in haemophila and platelet function disorders

30

What stimulates red blood cell production?

Decreased O2 supply
Erythropoetin produced by the kidneys