What tests diagnose lymphedema?

Diagnostic Testing for Lymphedema

Lymphoscintigraphy is the gold standard for detecting lymphatic system impairment and should be used as the primary diagnostic test for lymphedema. 1

Primary Diagnostic Methods

Clinical Examination

• Assess for pitting or non-pitting edema, fibrosis, and overall tissue quality 2
• Look for characteristic skin changes such as peau d'orange appearance 1
• Use the Stemmer sign: inability to lift skin at the base of second toe/finger compared to contralateral limb 2
• Document self-reported symptoms of swelling, heaviness, and numbness 2

Objective Measurements

1. Circumferential Measurement

   • Diagnostic when showing ≥2 cm increase compared to unaffected limb 1
   • Essential for diagnosing upper extremity lymphedema at Stage 1 or greater 2
   • For hand lymphedema: figure-of-8 method of measurement 2, 1
   • For head and neck: measurement at single point under jawline 2, 1

2. Volume Measurement

   • Water displacement: diagnostic with >200 mL difference or >10% interlimb difference 2
   • Volume ratio of 1.04 may indicate upper extremity lymphedema 2

3. Bioimpedance Analysis (BIA)

   • Detects lymphatic transport impairments and subclinical/early stage lymphedema 2, 1
   • L-Dex score >7.1 is diagnostic when no preoperative assessment is available 2
   • L-Dex score >10 above preoperative baseline is diagnostic 2
   • Note: In moderate to late stages with fibrosis, BIA may show decreased extracellular fluid despite increased tissue volume 2

Advanced Imaging Techniques

First-Line Advanced Imaging

• Lymphoscintigraphy: Gold standard for detecting lymphatic system impairment 2, 1
• Ultrasound: Useful as a diagnostic tool and to identify tissue changes 2

Additional Imaging Options

• Magnetic Resonance Imaging (MRI): Can be used as a diagnostic tool 2, 3
• Magnetic Resonance Lymphangiography (MRL): Superior to lymphoscintigraphy in visualizing lymphatics 3
• Computed Tomography (CT): Can be used as a diagnostic tool 2
• Lymphography: Useful for detecting lymphatic system impairment 2

Questionnaires for Diagnosis

• Norman Questionnaire 2
• Morbidity Screening Tool 2

Differential Diagnosis Considerations

• Distinguish lymphedema from other causes of edema using the Stemmer sign 2
• Rule out edema from increased hydrostatic pressure (cardiac, cirrhosis, renal failure) 2
• Rule out edema from decreased oncotic pressure 2

Testing Not Recommended

• Tonometry is not recommended as a diagnostic tool 2
• Perometry may be used for assessment of volume but not as a diagnostic tool 2
• Tissue Dielectric Constant should not be used as a diagnostic tool (only for assessment) 2
• Dual-energy X-Ray Absorptiometry should not be used as a diagnostic tool (only for assessment) 2

Diagnostic Algorithm

1. Begin with clinical examination and Stemmer sign
2. Perform circumferential measurements comparing affected vs. unaffected limbs
3. If diagnosis remains unclear, proceed to bioimpedance analysis
4. For definitive diagnosis or to evaluate lymphatic function, order lymphoscintigraphy
5. For detailed anatomical assessment or in complex cases, consider MRI/MRL or CT

Important Considerations

• Early diagnosis is critical for better outcomes - investigate self-reported symptoms promptly 2
• Most asymptomatic limbs (81.4%) in patients with unilateral lymphedema show abnormal findings on advanced imaging 3
• In primary lymphedema, collateral lymphatic pathways may appear less frequently than in secondary lymphedema 3
• Consider risk factors such as cancer treatment (especially breast cancer with radiation) and obesity 1