Coagulation Testing Lab

Question 1

Why is Ca added to the test tubes for aPPT and PT?

Answer 1

Because the tubes had a chelator that sequestered Ca so clotting wouldn’t take place until we wanted it to. So we need to add the Ca back in

Question 2

What part of a CBC is a screening test for the cause of bleeding

Answer 2

Platelet count

Question 3

Hx: petechiae, platelet count well within the reference range
Why glycoprotein is likely responsible for the bleeding?

Answer 3

von Willebrand factor

Question 4

When doing a coag test, what needs to be added to the tube in order to ‘set off’ the coagulation cascade?

Answer 4

PT: TF (III), Ca and phospholipid source
aPTT: contact activation to activate factor XII, Ca and phospholipid source

Question 5

What factor can be evaluated using PT but not aPTT?

Answer 5

VII

Question 6

What factors in evaluated by an aPTT test are associated with clinical bleeding and what pathway are they part of

Answer 6

Intrinsic. IX, VIII

Question 7

If aPTT and PT are both prolonged, what factor(s) is likely the problem?

Answer 7

II, VII, IX, or X

Question 8

Which factor has the shortest half-life

Answer 8

VII

Question 9

If an animal is developing liver failure, which coag test is likely to be slow (first)

Answer 9

PT - because VII has the shortest half life so will be the first to be depleted

Question 10

Hx: severe bleeding, prolonged aPTT, normal PT
What’s the problem?

Answer 10

VIII or IX (hemophiliac)

Question 11

What process is the blue arrow showing
What is the red arrow pointing at

Answer 11

Platelet aggregation
Fibrinogen

Question 12

Hx: scooching along carpet –> relatively severe sub-q hemorrhages, aPTT and PT are prolonged with minor thrombocytopenia, normal biochemistry panel
Explanation?

Answer 12

Rodenticide ingestion –> no vit K reduction –> no glutamic acid residues on factors II, VII, IX, X –> they don’t work