What is the recommended workup for a patient with unexplained bruising?

Diagnostic Workup for Unexplained Bruising

The recommended workup for a patient with unexplained bruising should begin with a bleeding assessment tool (BAT), followed by first-line laboratory tests including complete blood count, prothrombin time, activated partial thromboplastin time, and von Willebrand factor screening, with subsequent specialized testing based on initial results. 1

Initial Assessment

Clinical Evaluation

• Use a standardized bleeding assessment tool (BAT) to quantify bleeding severity 1
• Document specific bleeding patterns:
  • Unexplained or extensive bruising
  • Epistaxis (nosebleeds)
  • Menorrhagia in women
  • Excessive bleeding during childbirth or procedures
  • Bleeding from dental extractions 1
• Evaluate for medication use that may affect hemostasis
• Assess for family history of bleeding disorders
• Document timing, location, and circumstances of bruising
• Consider photographing bruises for documentation

First-Line Laboratory Tests

1. Complete blood count (CBC) with platelet count
2. Peripheral blood smear examination
3. Prothrombin time (PT) and International Normalized Ratio (INR)
4. Activated partial thromboplastin time (aPTT)
5. Von Willebrand factor (VWF) screening:
   • VWF antigen (VWF:Ag)
   • VWF ristocetin cofactor activity (VWF:RCo)
   • Factor VIII coagulant activity (FVIII:C) 1, 2

Interpretation of Initial Test Results

Normal PT and aPTT

• Suggests platelet disorder or von Willebrand disease (most common inherited bleeding disorder)
• Proceed with:
  • Light transmission aggregometry (LTA) with epinephrine, ADP, collagen, arachidonic acid, and ristocetin 1
  • Assessment of platelet granule release
  • Flow cytometry analysis of platelet surface glycoproteins 1

Normal PT, Prolonged aPTT

• Indicates disorder of the intrinsic coagulation pathway
• Perform mixing study to differentiate between factor deficiency and inhibitor
• Test for specific factor levels (VIII, IX, XI) 2, 3

Prolonged PT, Normal aPTT

• Suggests disorder of the extrinsic coagulation pathway
• Consider vitamin K deficiency or factor VII deficiency
• Perform vitamin K challenge if appropriate 3

Both PT and aPTT Prolonged

• Consider liver disease, DIC, or multiple factor deficiencies
• Measure fibrinogen levels
• Evaluate for liver dysfunction 3

Second-Line Testing

If first-line tests are normal but clinical suspicion remains high:

1. Platelet function testing (60% of specialists recommend as second-line) 1
2. Additional coagulation factor assays:
   • Factor II (52%)
   • Factor V (55%)
   • Factor VII (54%)
   • Factor X (53%)
   • Factor XIII (60%) 1
3. Platelet flow cytometry (42%) 1
4. Genetic testing (48%) 1
5. Fibrinolysis assays (38%) 1
6. Thrombin generation assay (28%) 1

Special Considerations

Pediatric Patients

• Always consider non-accidental trauma in children with unexplained bruising 1, 4
• Evaluate for vitamin K deficiency in infants 1
• Screen for immune thrombocytopenia (ITP) at time of presentation 1

Women with Easy Bruising

• Evaluate for iron deficiency and thyroid function 1, 5
• Consider hormonal influences on coagulation 5
• Assess for von Willebrand disease, which is more commonly symptomatic in women 3, 5

When to Refer to Hematology

• Abnormal initial laboratory tests
• Strong family history of bleeding disorders
• High clinical suspicion despite normal initial testing
• Need for specialized testing not available in primary care 1, 2, 3

Common Pitfalls to Avoid

• Relying on a single test to rule out bleeding disorders
• Failing to repeat testing when clinical suspicion remains high
• Not considering acquired causes of bleeding (medications, liver disease)
• Overlooking mild forms of von Willebrand disease that may have normal screening tests
• Dismissing patient concerns when initial tests are normal 1, 6

Remember that up to 60-70% of patients investigated for mild-moderate bleeding disorders may have bleeding of unknown cause (BDUC) with normal standard laboratory tests 1. If clinical suspicion remains high despite normal testing, referral to a hematologist is warranted for more specialized evaluation.