Disorders Of Hemostasis

Question 1

What is the clinical presentation for disorders of primary hemostasis (4)?

Answer 1

(1) Mucocuteneous Bleeding
(2) Easy Bruising
(3) Heavy Menstrual Bleeding
(4) Petichiae

Question 2

How do patients present with disorders of secondary hemostasis (3)?

Answer 2

(1) Hemarthrosis
(2) Intramuscular Bleeding
(3) Retroperitoneal Bleeding

Question 3

What are the factors of the extrinsic pathway of secondary hemostasis?

Answer 3

Factor VII

Tissue Factor

Question 4

What are the factors of the intrinsic pathway of secondary hemostasis?

Answer 4

Factors XII, XI, IX, VIII

Question 5

What are the components of the common pathway of secondary hemostasis?

Answer 5

Factors II (Prothrombin), V, X
Fibrinogen (Factor I)

Question 6

Which factors does warfarin affect?

Answer 6

II, VII, IX, X

Question 7

How do you evaluate an elevated INR (PT)?

Answer 7

50:50 mixing study:

(A) INR/PT corrects = Factor Deficiency (Ddx includes FVII deficiency, vitamin K deficiency, liver disease).

(B) INR/PT does NOT correct: inhibitor present (ddx includes lupus anticoagulant, possible FVII inhibitor)

Question 8

How do you evaluate an elevated aPTT?

Answer 8

50:50 mixing study interpretation:

(1) aPTT corrects = factor deficiency
(2) aPTT does not correct = inhibitor present

Question 9

How would you investigate a patient with an elevated aPTT & PT?

Answer 9

50:50 Mixing Study Interpretation:

(A) Corrects = Factor Deficiency (Measure FII, V, X) -> if factor low, deficiency confirmed

(B) Does NOT correct = Inhibitor (rule out lupus anticoagulant, measure FII, V, X and then the inhibitor for the factor that is low)

Question 10

What would you send to investigate for Von Willebrand disease (3)?

Answer 10

VWF Ag (Quantity)
Ristocetin Cofactor (VWF activity)
Factor VIII Level

aPTT can be normal and IS NOT a good screening test

Question 11

What are the components of cryoprecipitate?

Answer 11

Factor I (Fibrinogen)
Factor VIII
Factor XIII
Von Willebrand Factor
Fibronectin

Question 12

What are the different types of Von Willebrand disease?

Answer 12

Type I: Quantitative Deficiency
Type II: Qualitative Deficiency
Type III: No VWF produced (behaves like Hemophilia A)

Question 13

How would you manage a women with VWD and heavy menstrual bleeding?

Answer 13

ASH guidelines recommend OCP and TXA over desmopressin use.

Question 14

How would you manage a patient who has Von Willebrand Disease who presents to hospital with minor bleeding or requires a minor surgical procedure?

Answer 14

Type I: DDAVP (not in most Type II or III), +/- concentrates of VWF and FVIII

Type I or III: Will require cryopreciptate or concentrates of VWF and FVIII (Humate P)

Question 15

What is the target FIII and VWF activity level after surgery?

Answer 15

Target for both is > or = 0.5 IU/mL for at least 3 days post-op.

Question 16

What is the definition of ITP?

Answer 16

Platelets < 100 with an absence of other causes.

Question 17

When would you treat a patient with ITP?

Answer 17

(1) Not bleeding & platelets < 30:
A. First-Line: Steroids (Pred or Dex), IVIG, anti-D
B. Second-Line: Splenectomy, Rituximab, TPO-R agonists

(2) Active Bleeding
A. Steroids + TXA + IVIg
B. Life threatening - Plt transfusion +/- splenectomy

Question 18

When/how would you treat ITP in pregnancy?

Answer 18

(1) Bleeding
(2) Delivery
(3) Platelets < 50 + GA > or = 36 weeks

Prednisone (not dex - crosses the placenta)
IVIg

Target platelets > 50 for delivery & > 80 for neuraxial anasthesia

Question 19

When would you admit a newly diagnosed ITP patient?

Answer 19

If their platelets are < 20

Question 20

How do you interpret the results of the 4T score for heparin induced thrombocytopenia?

Answer 20

(1) Score < or = 3: Low probability (Rules out HIT)

Stop heparin, start alternate anticoagulation and send heparin immunoassay if:

(2) Score 4-5: Intermediate probability
(3) Score 6-8: High probability

Question 21

How would you manage suspected HIT?

Answer 21

(1) Alternative Anticoagulant (argatroban, danaparoid)
(2) Bilateral Leg Dopplers
(3) If HIT confirmed, start warfarin when platelets > 150, target INR 2-3 and continue for 1 month if no thrombosis, or 3 months if thrombosis is present.

Question 22

How do you rule out thrombocytopenia?

Answer 22

Repeat CBC with platelets count in a citrate tube (blue top) rather than an EDTA tube.