For a suspicion of lymphedema, should I do an ultrasound (US) of the upper extremity veins or arteries?

Ultrasound for Suspected Lymphedema of the Upper Extremity

For suspected lymphedema of the upper extremity, a venous ultrasound duplex Doppler examination should be performed rather than an arterial study. 1

Rationale for Venous Ultrasound in Lymphedema

• Venous ultrasound is the preferred initial imaging modality for evaluating suspected lymphedema as it can help rule out venous obstruction (such as deep vein thrombosis) which can mimic or contribute to lymphedema symptoms 1
• Ultrasound duplex Doppler is a noninvasive test that can be performed at bedside and used for serial evaluations to monitor progression or response to treatment 1
• The examination allows for direct visualization of venous structures and can identify:
  • Venous obstruction or thrombosis that may be contributing to edema 1
  • Lymphatic vessel degeneration and abnormal expansion which are hallmarks of lymphedema 2
  • Subcutaneous tissue changes characteristic of lymphedema 3

Ultrasound Technique for Lymphedema Evaluation

• The examination should focus on:
  • Venous structures to rule out venous obstruction or thrombosis 1
  • Subcutaneous tissue to identify low-density spaces that may correspond to dilated lymphatic channels 3
  • Tissue thickness and echogenicity changes in the affected limb compared to the contralateral side 4
  • Lymphatic vessels which may show abnormal expansion or sclerosis in lymphedema 2

Advantages of Venous Ultrasound Over Arterial Studies

• Lymphedema is primarily a disorder of lymphatic drainage, not arterial supply 5
• Venous pathology (such as DVT) more commonly mimics lymphedema symptoms than arterial disease 1
• Venous ultrasound can assess both the venous system and surrounding soft tissues for lymphedema-specific changes 2, 3
• Recent studies have demonstrated high sensitivity (95%) and specificity (100%) for diagnosing lymphedema using ultrasound evaluation of lymphatic vessels 2

Clinical Applications of Ultrasound in Lymphedema

• Diagnostic differentiation between:
  • Primary lymphedema
  • Secondary lymphedema (e.g., post-breast cancer treatment)
  • Venous obstruction/insufficiency
  • Other causes of extremity swelling 5, 3
• Assessment of lymphedema severity through evaluation of:
  • Soft tissue thickness and texture changes 4
  • Degree of lymphatic vessel degeneration 2
• Monitoring response to therapeutic interventions 4
• Surgical planning for procedures such as lymphovenous anastomosis 4

Common Pitfalls to Avoid

• Failure to examine both the affected and unaffected limbs for comparison 2
• Not evaluating both superficial and deep venous systems 1
• Overlooking the importance of assessing subcutaneous tissue changes characteristic of lymphedema 3
• Missing lymphatic vessels which require high-frequency probes (18 MHz) and specific scanning techniques for optimal visualization 2