What is the approach to investigating spontaneous bruising on the legs?

Approach to Investigating Spontaneous Bruising on the Legs

The initial evaluation of spontaneous bruising on the legs should include a comprehensive medical history, physical examination, and targeted laboratory testing to rule out bleeding disorders, with specific attention to age, location of bruising, and risk factors for peripheral artery disease in adults.

Initial Assessment

Medical History - Key Elements

• Age of onset and pattern of bruising
• Medication use (anticoagulants, antiplatelet agents, NSAIDs)
• Family history of bleeding disorders or easy bruising
• Previous excessive bleeding after surgery, dental procedures, or childbirth
• Associated symptoms (joint pain, fatigue, leg pain with walking)
• History of trauma (even minor)

Physical Examination - Critical Findings

• Distribution and characteristics of bruises
  • Symmetrical vs. asymmetrical
  • Size, shape, and color (aging pattern)
  • Presence of petechiae
• Vascular examination
  • Palpation of lower extremity pulses (femoral, popliteal, dorsalis pedis, posterior tibial)
  • Auscultation for femoral bruits
  • Blood pressure measurement in both arms (difference >15-20 mmHg suggests subclavian stenosis) 1
• Joint hypermobility or skin hyperextensibility (suggesting connective tissue disorders)

Laboratory Evaluation

Initial Screening Tests

• Complete blood count with platelet count
• Prothrombin time (PT)
• Partial thromboplastin time (PTT)
• Bleeding time or PFA-100 (Platelet Function Analyzer)

Additional Tests Based on Initial Findings

• If abnormal platelet count: peripheral blood smear examination
• If normal initial screening but strong history of bleeding: von Willebrand factor antigen and activity
• If suspicion for connective tissue disorder: consider genetic testing for Ehlers-Danlos syndrome 2
• If vascular concerns in adults: ankle-brachial index (ABI) 1

Special Considerations by Age Group

Children

For children with spontaneous bruising, special attention must be paid to:

• Location of bruising (bruising in unusual locations such as ears, buttocks, or genitals raises concern for abuse) 1
• Developmental stage (non-mobile infants should not have bruises)
• Consistency of history with developmental capabilities
• Need for evaluation of non-accidental trauma in suspicious cases 1

Adults

In adults, consider:

• Peripheral artery disease, especially in those with risk factors (diabetes, smoking, hypertension, hyperlipidemia) 1
• Age-related skin changes leading to increased capillary fragility
• Medication effects (anticoagulants, steroids)
• "Easy bruising syndrome" - more common in women with normal platelet counts 3, 4

Diagnostic Algorithms

For Isolated Leg Bruising in Adults:

1. If bruising is accompanied by leg pain with exertion, diminished pulses, or other signs of vascular insufficiency:

   • Perform ABI measurement
   • Consider vascular specialist referral if ABI <0.9 1

2. If bruising is isolated without vascular symptoms:

   • Perform basic coagulation screening (CBC, PT, PTT)
   • If normal and history strongly suggests bleeding tendency, consider specialized hemostasis testing 3

For Bruising in Children:

1. If bruising is in typical locations for accidental injury (shins, knees, forehead) in mobile children:

   • Basic coagulation screening if extensive or recurrent
   • Reassurance if isolated and age-appropriate

2. If bruising is in unusual locations or patterns:

   • Complete coagulation workup
   • Consider child protection evaluation if medical causes excluded 1

Common Pitfalls to Avoid

• Assuming all bruising in women with "easy bruising" is benign without appropriate screening 3
• Failing to consider non-accidental trauma in children with suspicious bruising patterns 1
• Missing peripheral vascular disease in older adults with leg bruising 1
• Overlooking connective tissue disorders like Ehlers-Danlos syndrome, which can cause easy bruising despite normal coagulation tests 2

By following this structured approach to investigating spontaneous bruising on the legs, clinicians can efficiently identify or rule out serious underlying conditions while providing appropriate management for patients.