Coagulation Testing

Question 1

when should you perform coagulation testing?

Answer 1

unexplained bleeding
pre-operative testing
monitoring anticoagulation

Question 2

what is tissue factor?

Answer 2

potent coagulator, usually inside cells
release triggered by inflammation

Question 3

what does PT test?

Answer 3

extrinsic pathway of coagulation

Question 4

what does aPTT test?

Answer 4

intrinsic pathway of coagulation

Question 5

what factor is in the extrinsic pathway?

Answer 5

factor VII

Question 6

what are the commonly available coagulation tests?

Answer 6

prothrombin time (PT)
activated partial thromboplastin time (aPTT)
thrombin time
fibrinogen
platelet count
vWF assay
viscoelastic testing: thromboelastography, VCM

Question 7

what should be avoided when collecting a sample to use for coagulation testing?

Answer 7

probing for vessel
excessive vacuum

Question 8

when mixing citrate with blood, what is the correct ratio?

Answer 8

one part citrate
nine parts blood

Question 9

what is mild thrombocytopenia?

Answer 9

150,000-200,000/ul

Question 10

what is moderate thrombocytopenia?

Answer 10

100,000-150,000/ul

Question 11

what is severe thrombocytopenia?

Answer 11

50,000-100,000/ul

Question 12

what is profound thrombocytopenia?

Answer 12

<50,000/ul

Question 13

what should you think about if you have platelet bleeding but a normal platelet count?

Answer 13

platelet function

Question 14

what are some things that impact platelet function?

Answer 14

Von Willebrand’s disease
uremia
drugs

Question 15

what can you use to test for platelet function?

Answer 15

buccal mucosal bleeding time

Question 16

what does the extrinsic pathway start with?

Answer 16

tissue factor expression

Question 17

why might a patient have a prolonged PT?

Answer 17

vitamin K deficiency
anticoagulant rodenticide toxicity
liver failure

Question 18

what is factor VII dependent upon?

Answer 18

vitamin K

Question 19

what test should you use to check for hemophilia?

Answer 19

aPTT

Question 20

what might a prolonged aPTT mean?

Answer 20

acquired and hereditary disorders
hemophilia A and B
anticoagulation with heparin

Question 21

what does thrombin time measure?

Answer 21

‘functional’ fibrinogen

Question 22

what might cause hypofibrinogenemia?

Answer 22

DIC
liver failure
bleeding- consumption

Question 23

what might a shortened PT/aPTT mean?

Answer 23

maybe hypercoagulable state

Question 24

what are fibrinogen degradation products?

Answer 24

fibrin degradation product
D-dimer

Question 25

what is D-dimer useful for?

Answer 25

if super high: maybe helpful negative predictive value

Question 26

what can a thromboelastography test tell us?

Answer 26

hemostatic changes hypercoagulability fibrinolysis

Question 27

when might you see hyperfibrinolysis?

Answer 27

greyhounds trauma bleeding states (hemoperitoneum) acute liver disease

Question 28

what are some common coagulopathies?

Answer 28

thrombocytopenia von willebrand's disease anticoagulant rodenticide DIC

Question 29

what are some less common coagulopathies?

Answer 29

dilutional traumatic hemophilia drug-induced

Question 30

what tests can you use to look for von willebrand's disease?

Answer 30

index of suspicion vWF assay or buccal mucosal bleeding time

Question 31

what are the positives of doing a blood smear?

Answer 31

cage-side platelet count inexpensive rapid scan to look for clumping immediate result avoid delay in therapy drive diagnostic planning serial monitoring

Question 32

how do we treat ITP?

Answer 32

immunosuppressives vincristine whole blood or packed red blood cell transfusions

Question 33

should you do platelet transfusions in ITP?

Answer 33

only if bleeding out

Question 34

when should you consider the potential role of hyperfibrinolysis?

Answer 34

bleeding: spontaneous or traumatic hemoabdomen

Question 35

what does dilutional coagulopathy follow?

Answer 35

fluid resuscitation

Question 36

when is dilutional coagulopathy most significant?

Answer 36

surgical diseases

Question 37

do platelet blockers affect the platelet count?

Answer 37

no

Question 38

what are the tests for monitoring anticoagulation?

Answer 38

aPTT anti-Xa activity

Question 39

what does anti-Xa activity test?

Answer 39

low molecular weight heparin

Question 40

what can cause hypercoagulability?

Answer 40

systemic inflammation empiric anticoagulation

Question 41

what laboratory findings might point towards a hypercoagulable state?

Answer 41

shortened PT/aPTT mild thrombocytopenia fibrin(ogen) degradation products D-dimers

Question 42

what do cytokines stimulate?

Answer 42

hypercoagulable state

Question 43

what are the endogenous anticoagulants?

Answer 43

protein C, antithrombin decreased in inflammatory disease states

Question 44

what is the D-dimer assay specific for?

Answer 44

FDP fragment fibrin breakdown

Question 45

fibrin formation has to have occurred for ________________ to be present

Answer 45

D-dimers

Question 46

how can sodium citrate be reversed?

Answer 46

addition of excess calcium

Question 47

what is the contact activator with activated clotting time?

Answer 47

diatomaceous earth

Question 48

what are the normal values of activated clotting time in dogs and cats?

Answer 48

dogs <120 seconds cats <180 seconds

Question 49

what is activated clotting time used for?

Answer 49

titrate heparin in hemodialysis

Question 50

when does hypofibrinogenemia occur?

Answer 50

DIC liver failure bleeding

Question 51

is D-dimer or FDPs more specific for fibrinolysis?

Answer 51

D-dimer

Question 52

what test can you use for hemophilia?

Answer 52

aPTT

Question 53

what tests can you use for trauma testing coagulopathies?

Answer 53

PT aPTT TEG

Question 54

what tests can you use for dilutional coagulation testing?

Answer 54

PT aPTT

Question 55

does the factor percent in hemophilia impact outcome?

Answer 55

no

Question 56

what are some common causes of unexplained bleeding?

Answer 56

anticoagulant rodenticide toxicity ITP trauma heatstroke dilution hemangiosarcoma

Question 57

what should you do if dilutional coagulopathy is prolonged?

Answer 57

plasma transfusion

Question 58

what anticoagulants get down-regulated by cytokines?

Answer 58

protein C antithrombin

Question 59

what does the test for fibrin degradation products measure?

Answer 59

breakdown of fibrin and fibrinogen: not specific

Question 60

what do increased values of fibrin degradation products indicate?

Answer 60

fibrinolysis has occured

Question 61

fibrin formation has to have occurred for ________________ to be present

Answer 61

D-dimers