7. evaluation of the coagulation system

Question 1

what are the screening tests used in abnormal hemostasis?

Answer 1

PT, PTT, thrombin time
mixing studies (patients plasma with normal plasma 1:1)–> coagulation factor levels
fibrinogen assay
D-dimer assay
CBC
bleeding time
platelet aggregation assay - measure aggregation in response to agonists (ADP)

Question 2

non-palpable purpura

Answer 2

• PLT disorder: thrombocytopenia, defects of platelet function
• Thromboemboli: DIC, TTP, cholesterol or fat emboli
• Trauma or vascular fragility: scurvy, Ehlers-Danlos syndrome

Question 3

palpable purpura

Answer 3

• Vasculitis

- infectious endocarditis

Question 4

what is the site and lesion of a platelet/vascular defect (primary hemostasis)?

Answer 4

seen in the skin, mucous membranes

lesion: petechiae, purpura

Question 5

what is the site and lesion of a coagulation defect (secondary hemostasis)?

Answer 5

seen in the deep soft tissues (muscle, joints)

lesion: Hemarthrosis, hematomas