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Flashcards in HAEM - bleeding disorders Deck (36):
1

What does Activated Partial thromboplastin time (APTT) measure?

Intrinsic pathway coagulation (factors 8, 9, 11, 12)

Surface activating agent (Ellagic acid, kaolin)
Phospholipid
Calcium

2

What does Prothrombin time (PT) measure?

Extrinsic pathway (factor 7)

(remember PT is used for INR and INR is related to vitamin K & warfarin. Vitamin K helps produce factors 2, 7, 9, 10, and factor 7 is uniquely in EXTRINSIC - hence it measures extrinsic pathway)

3

What does Thrombin time measure?

Common pathway

4

(4) features of screening tests for hemostatic defects

-Platelet Count (150 - 400)
-Activated Partial Thromboplastin Time (Aptt) (24-32 Seconds)
-Prothrombin Time(pt)(10 -12 Seconds)
-Thrombin Time

5

How can you differentiate factor deficiency from presence of 'inhibitor' in coagulation?

Perform Mixing study:
Mix 1/2Pt + 1/2 Control (CONTROL - POOLED PLASMA from normal individuals) and perform APTT or PT

•If factor deficiency = APTT / PT will normalize (the control pool will make up for the deficiency)
•If ‘inhibitor’present = persistent abnormality (inhibitor will affect the control pool also)

6

(3) Causes of corrected APTT after Mixing study in previously normal PT, prolonged APTT

- Factor deficiency (VIII, IX, XI, XII)
- Early DIC
- Heparin Rx (variable correction)

7

(2) Causes of persistent abnormality after Mixing study in previously normal PT, prolonged APTT

- Lupus anticoagulant (common)
- Inhibitors towards specific coagulant factors VIII, IX, XI

8

(3) Causes of corrected PT after Mixing study in previously prolonged PT, normal APTT

- Factor deficiency (VII)-rare
- Liver disease, Vit K defi
- Warfain (above are common)

9

(2) Causes of persistent abnormality after Mixing study in previously prolonged PT, normal APTT

- Antiphospholipid ab’s: uncommon
- Antibodies to VII: rare

10

(2) Causes of corrected PT/APTT after Mixing study in previously prolonged PT, prolonged APTT

- Isolated deficiency in common pathway: Factors V, X, II, and fibrinogen

- Multiple factor deficiencies (common): Liver disease, vitamin K deficiency, warfarin, DIC

11

(3) Causes of persistent abnormality after Mixing study in previously prolonged PT, prolonged APTT

- Inhibitors towards V, X, II
- fibrinogen (rare)
- anti-phospholipid ab’s

12

(5) causes of prolonged PT

-Warfarin (F II, VII, IX, X)
-Liver disease
-Vitamin K deficiency
-DIC
- Factor VII deficiency

13

(7) causes of prolonged APTT

-Heparin anticoagulation therapy
-Liver disease
-Lupus anticoagulant
-DIC
-von Willebrand’s disease
-Haemophilia: Factor VIII, Factor IX deficiency
-Factor XII, XI deficiency

14

(3) causes of prolonged thrombin time (TT)

-DIC (decreased fibringogen)
-Liver disease
-Heparin

15

Describe purpuric disorders
- petechiae
- superficial echymoses
- haematoma & haemarthrosis
- late bleed
- gender
- FMHx

Purpuric disorders have characteristic petechiae, small & multiple superficial echmoses
- rare haematoma, haemarthrosis
- rare late bleed
- females > males
- variable FMHx

16

Describe coagulation disorders
- petechiae
- superficial echymoses
- haematoma & haemarthrosis
- late bleed
- gender
- FMHx

Coagulation disorders have rare petechiae, large & solitary superficial echymoses
- characteristic haematoma & haemarthrosis
- common late bleed
- 80-90% males
- common FMHx

17

(4) Common hereditary bleeding disorders

•Hemophilia – A /B
•Von Willebrand disease
•Factor deficiency
•Platelet Disorders

18

(5) common acquired bleeding disorders

–Liver disease
–Vit K deficiency
–DIC
–Excessive anticoagulation
–ITP (idiopathic thrombocytopaenic purpura)

19

(2) functions of vWF

1. vWF mediates platelet adhesion at site of injury

2. Stabilizes FVIII in circulation

Remember: Wherever platelet aggregation is needed, coagulation is also necessary. vWF is like a ‘taxi’ that carries fVIII to the proximity of a developing clot

20

What modifies penetrance of type I von Willebrand disease?

ABO group

•ABO glycosylation of vWF influences clearance
•People with non-O blood group have higher levels compared with O-group
•Blood group AB people have highest level

21

Describe type 1, 2, 3 of von Willebrand's disease

Type 1 -partial quantitative deficiency of VWF
–70-80% cases- Ad
–Mild presentation / blood group.

Type 2 -qualitative deficiency of VWF
- Subtypes : Differences in multimers
- Mild to moderate bleeding.
- Abnormal Multimers

Type 3- virtually complete deficiency of VWF

All have prolonged APTT

22

Specific Ix for vWD (von Willebrand's disease)

- von Willebrand Factor Antigen (vWAg)
- Factor VIII clotting activity : VIII C
- Functional assays : Ristocetin Co-Factor activity/Collagen-binding assay

23

Rx for vWD

•Desmopressin (DDAVP): Releasing FVIII & vWFAg from storage sites. Effective in Type 1.
•Replacement Therapy
•Antifibrinolytics - Tranexamic acid
•Fibrin Glue / Fibrillar collagen preparation

24

Explain pathophysiology of haemophilia A
- factors involved
- genetics

–Factor VIII deficiency
–F VIII normally circulates bound to vWf, which protects F VIII from proteolysis

Genetics:
–X-linked recessive (gene on X chromosome)
–Males present with features of disease (males = XY)

25

Clinical Px of haemophilia A

–Hemarthrosis
–Subcutaneous and intramuscular haematomas
–Psoas and retroperitoneal haematomas
–Traumatic bleeding:
•Bleeding from razor nicks is uncommon
•Delayed bleeding is common especially in tooth extractions, tonsillectomy
•Wound healing is slow in haemophiliacs

26

Which clotting profile would be abnormal in haeomphilia A?

APTT (factor 8 deficient)

INR is normal

27

Rx of haemophilia A

–Purified or Recombinant F VIII therapy
–Tranexamic acid
–Topical thrombin
–Role of FFP

28

Describe haemophilia B
- factor involved
- prevalance compared to haem A
- genetic

•Factor IX deficiency
•4-8 times less common than Haemophilia A
•X-linked recessive
•Unlike Haemophilia A, spontaneous mutation rate is low, most patients have family history
•Severe disease manifests identical to Haemophilia A

29

Which factor is deficient in haemophilia A?

Factor 8

30

Which factor is deficient in haemophilia B?

Factor 9

31

Ix of haemophilia B

–Prolonged APTT (factor 9 deficiency), Normal INR
–APTT not sensitive to mild deficiency (F IX 20-30%)

32

Rx of haemophilia B

–Prothrombin complex
–Purified or Recombinant F IX

33

What is thrombocytopaenia?

deficiency of platelets in the blood.

This causes bleeding into the tissues, bruising, and slow blood clotting after injury

34

What are the causes of thrombocytopaenia?
- increased destruction
- decreased production

Increased destruction
1. Auto-Immune:
- ITP
- SLE etc
- Drugs

2. Allo-immune:
- Post Transfusion Purpura
- Neonatal Allo-Immune Thrombocytopenia

3. Non-immune:
- Hypersplenism
- DIC / TTP / HUS

Decreased production
- Aplastic Anaemia
- Myelodysplasia
- Leukaemic infiltration
- Lymphoma infiltration
- Fibrosis

35

Where do you typically bleed in thrombocytopaenia?

•Skin and mucous membranes
–Petechiae
–Ecchymosis
–Hemorrhagic vesicles
–Gingival bleeding and epistaxis

•Menorrhagia
•Gastrointestinal bleeding
•Intracranial bleeding

36

(4) How do you assess the function of platelets?

1. Thromboelastography (TEG)

2. PLATELET AGGREGATION STUDIES
- ADP
- COLLAGEN
- ADRENALINE
- RISTOCETIN

3. Plt Function Analysis (PFA)

4. Skin Bleeding Time: No longer preferred as technical issues of standardization and expertise

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