What laboratory tests are recommended for a patient presenting with easy bruising?

Laboratory Tests for Patients Presenting with Easy Bruising

For patients presenting with easy bruising, the recommended initial laboratory workup should include a complete blood count (CBC) with platelet count, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen levels, and von Willebrand factor (VWF) assays. 1

Initial Screening Tests

The core initial laboratory evaluation should include:

1. Complete Blood Count (CBC) with platelet count

   • Essential for identifying thrombocytopenia or other blood cell abnormalities 1
   • Low platelet count may indicate immune thrombocytopenia (ITP) or other causes of platelet destruction 2

2. Coagulation screening

   • Prothrombin Time (PT) - evaluates extrinsic and common pathways 1
   • Activated Partial Thromboplastin Time (aPTT) - evaluates intrinsic and common pathways 1
   • Fibrinogen levels - performed by 90% of specialists as part of first-line testing 1

3. Von Willebrand Factor (VWF) assays

   • Performed by 84% of specialists 1
   • Should include VWF antigen (VWF:Ag), VWF ristocetin cofactor activity (VWF:RCo), factor VIII coagulant activity (FVIII:C) 1
   • Critical because von Willebrand disease is the most common inherited bleeding disorder and is not reliably detected by PT/aPTT 3, 4

Interpretation of Initial Results

• Normal PT and aPTT may indicate:

  • Platelet disorder (most commonly von Willebrand disease) 4, 5
  • Mild factor VIII or IX deficiency (mild hemophilia) that might not cause abnormalities in the aPTT but can still result in significant bleeding 3

• Normal PT and prolonged aPTT indicates:

  • Deficit in the intrinsic pathway - requires a mixing study 4, 5
  • Possible hemophilia A or B 2

• Prolonged PT and normal aPTT suggests:

  • Disorder of the extrinsic coagulation pathway 5
  • Possible vitamin K deficiency or factor VII deficiency 2

• Both PT and aPTT prolonged warrants:

  • Workup for liver failure 4
  • Consideration of multiple factor deficiencies 2

Additional Testing Based on Clinical Suspicion

If initial testing is normal but clinical suspicion remains high:

1. Platelet function testing

   • Performed by 60% of specialists 1
   • May require referral to a hematologist for proper interpretation 3
   • Can detect disorders like Bernard Soulier syndrome and Glanzmann thrombasthenia 3

2. Additional factor assays

   • Factor II, V, VII, X, and XIII 1
   • Factor XIII deficiency is not detected by routine PT/aPTT but can cause significant bleeding 3

3. Specialized testing

   • Thrombin time (TT) - helpful when suspecting disseminated intravascular coagulation or presence of heparin 2
   • Fibrinolytic defects testing - rare but can cause significant bleeding/bruising 3

Important Clinical Considerations

• A thorough bleeding assessment using a standardized Bleeding Assessment Tool (BAT) should accompany laboratory testing 1
• Family history of bleeding problems is crucial to identify hereditary coagulation defects, especially in children 1, 4
• Medication review is essential to identify pharmacologic causes of bleeding or bruising (especially NSAIDs) 1, 4
• Physical examination findings can guide testing:
  • Mucocutaneous bleeding suggests platelet dysfunction
  • Hemarthroses or hematomas are more common in coagulopathy 4

Common Pitfalls to Avoid

1. Failure to test for von Willebrand disease - Not reliably detected by PT/aPTT screening but is the most common inherited bleeding disorder 3, 4

2. Missing mild factor deficiencies - Mild hemophilia might not cause abnormalities in the aPTT but can still result in significant bleeding 3

3. Inadequate evaluation in women - Easy bruising is common in women, but a thorough evaluation is still warranted to rule out significant bleeding disorders 6

4. Not considering non-hematologic causes - In children, consider non-accidental trauma as a potential cause of bruising 3, 5

5. Stopping at normal screening tests - If clinical suspicion remains high despite normal initial testing, referral to a hematologist is recommended for additional evaluation 4, 5