Laboratory Evaluation for Increased Bruising
Initial laboratory evaluation for increased bruising should include complete blood count (CBC), prothrombin time (PT), activated partial thromboplastin time (PTT), and von Willebrand factor testing (VWF:Ag, VWF:RCo, and Factor VIII activity). 1, 2
Initial Screening Tests
The following tests should be ordered first:
- Complete blood count (CBC) with platelet count - To assess for thrombocytopenia or other hematologic abnormalities 1, 3
- Peripheral blood smear - To exclude pseudothrombocytopenia and identify morphological abnormalities 2
- Prothrombin time (PT)/International Normalized Ratio (INR) - To evaluate the extrinsic coagulation pathway 3, 4
- Activated partial thromboplastin time (PTT) - To evaluate the intrinsic coagulation pathway 3, 4
Interpretation of Initial Tests
- Normal PT and PTT: Suggests platelet disorder or von Willebrand disease (VWD) 4
- Normal PT, prolonged PTT: Indicates disorder of the intrinsic coagulation pathway; mixing study should be performed 3
- Prolonged PT, normal PTT: May indicate disorder of the extrinsic coagulation pathway 4
- Both PT and PTT prolonged: Consider liver disease, vitamin K deficiency, or DIC 3
Additional Testing for von Willebrand Disease
If initial screening tests are normal but clinical suspicion for a bleeding disorder remains high, especially with mucocutaneous bleeding pattern, proceed with VWD testing:
- VWF antigen (VWF:Ag) - Measures the amount of VWF protein 1
- VWF ristocetin cofactor activity (VWF:RCo) - Measures VWF function 1
- Factor VIII coagulant activity (FVIII) - Often decreased in VWD 1
Additional Considerations
- Fibrinogen - Should be measured if there is suspicion for consumptive coagulopathy 2
- D-dimer - May be useful to evaluate for consumptive coagulopathy 2
- Liver function tests - Necessary to rule out hepatic causes of coagulopathy 2
Special Situations
- For suspected acquired von Willebrand syndrome (AVWS): Consider the same VWD tests as above, particularly in patients with new-onset bleeding without personal or family history of bleeding disorders 1
- For suspected medication-induced bleeding: Conduct a thorough medication review focusing on anticoagulants, antiplatelet agents, and medications known to affect platelet function 3
Common Pitfalls to Avoid
- Relying solely on platelet count without examining peripheral blood smear can miss pseudothrombocytopenia 2
- Failure to consider von Willebrand disease, which is the most common inherited bleeding disorder 1, 3
- Not considering acquired causes of bleeding disorders, including medication effects 2
- Stopping the workup after normal PT and PTT results despite strong clinical suspicion of a bleeding disorder 4
If initial testing does not reveal an etiology in a patient with high suspicion for a bleeding disorder, referral to a hematologist is warranted for additional specialized testing 3, 4.