What is the initial blood workup for a patient presenting with easy bruising?

Initial Blood Workup for Easy Bruising

The initial blood workup for a patient presenting with easy bruising should include a complete blood count (CBC) with platelet count, prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen. 1

Primary Screening Tests

• Complete Blood Count (CBC) with platelet count

  • Evaluates for thrombocytopenia (low platelets), which is a common cause of easy bruising
  • Identifies other abnormalities in blood cells that might suggest underlying conditions

• Coagulation Studies

  • Prothrombin Time (PT) - Evaluates the extrinsic coagulation pathway
  • Activated Partial Thromboplastin Time (aPTT) - Evaluates the intrinsic coagulation pathway
  • Fibrinogen - Assesses for fibrinogen disorders

• Peripheral Blood Smear - To evaluate platelet size and morphology

Interpretation of Initial Results

• Normal PT and aPTT with low platelet count: Suggests immune thrombocytopenia (ITP) or other platelet disorders 2
• Normal PT with prolonged aPTT: Indicates a disorder of the intrinsic coagulation pathway (e.g., hemophilia A or B) 1
• Prolonged PT with normal aPTT: Suggests a disorder of the extrinsic coagulation pathway 1
• Both PT and aPTT prolonged: May indicate multiple factor deficiencies, vitamin K deficiency, or liver disease 2

Additional Testing Based on Initial Results

If initial screening tests are abnormal or if clinical suspicion remains high despite normal results, consider:

• Von Willebrand Factor (VWF) Panel 3

  • VWF antigen (VWF:Ag)
  • VWF ristocetin cofactor activity (VWF:RCo)
  • Factor VIII coagulant activity (FVIII:C)
  • VWF:RCo/VWF:Ag ratio

• Specialized Testing for Platelet Function

  • Platelet aggregation studies for suspected platelet function disorders
  • PFA-100 (Platelet Function Analyzer) may be useful but has limitations 2

Special Considerations

• Test for HIV and HCV in adult patients with suspected ITP, as these infections can cause secondary ITP 2
• Consider vitamin K deficiency in infants with bruising, which would show prolonged PT and possibly aPTT 2
• Thyroid function tests may be warranted as thyroid disorders can be associated with easy bruising and elevated platelet IgG 4

When to Consider Hematology Referral

• Abnormal initial laboratory workup
• Strong personal or family history of bleeding despite normal initial tests
• Severe or recurrent bleeding episodes
• Suspicion of rare bleeding disorders requiring specialized testing

Common Pitfalls to Avoid

1. Overlooking medication effects: Many medications (anticoagulants, antiplatelet agents, NSAIDs) can cause or worsen bruising
2. Failing to consider non-hematologic causes: Conditions like Ehlers-Danlos syndrome, scurvy, or elder abuse can present with easy bruising
3. Incomplete testing: Stopping at CBC without coagulation studies may miss important diagnoses
4. Over-testing: Not all patients with easy bruising require extensive workup; clinical context should guide testing

For most patients with easy bruising, these screening tests will adequately rule out significant bleeding disorders or identify which hemostatic mechanism requires further investigation 5.