Clinical Approach to Hemostasis

Question 1

Disorders of Primary Hemostasis. Defining features

Answer 1

thrombocytopenia, platelet function defects, von willebrand disease, vascular disorders.

these cause disturbances in platelet plug formation.

• Defining features:
– Present with mucocutaneous bleeding
– Involve superficial tissues
– Petechiae, purpura, epistaxis, mouth-related bleeding, menorrhagia
– Immediate bleeding
– May occur after minor trauma

Question 2

Lab tests to order primary hemostasis

Answer 2

CBC
PBS
VWF studies
Bleeding time/
closure time– more sensitive than bleeding time.
Platelet aggregation studies to assess platelet function abnormalities (done through light transmission studies)

Question 3

disorders of secondary hemostasis and defining features

Answer 3

Hemophilia A and B, coagulation factor deficiencies (could be caused by liver)

Defining features
– Hematomas, muscle bleeding, hemarthrosis, prolonged bleeding
– Involve deeper tissues : Look for significant hematomas. Look for joint DEFORMITIES which indicates previous bleeding events into joint spaces

– Bleeding is delayed and prolonged
– Bleeding is common after surgery

Question 4

lab tests for secondary hemostasis

Answer 4

secondary hemostasis prevents fibrin clot formation. therefore, tests to assess the coagulation cascade is important

PTT/aPTT for intrinsic pathway (TENET)
PT/INR for extrinsic (factor 7-TF) pathway
- use both to assess common pathway (factor 10+ 5a+ 2(thrombin))

Question 5

Thrombin time

Answer 5

measures conversion of fibrinogen to fibrin– final step oil clot formation
- irrespective of factor deficiencies in intrinsic/extrinsic cascade

• TT is affected by low fibrinogen levels, dysfunctional fibrinogen, or thrombin inhibitor.

Question 6

T/F everyone should be screened for coagulation disorder

Answer 6

false. screen only if history is positive. Coagulation screening for disease state (e.g. liver
disease, malabsorption, malnutrition) – not
appropriate. No justification for routine coagulation screening on all hospital admissions.