What is the workup for swelling in the lower legs?

Workup for Lower Leg Swelling

Begin with a focused vascular examination to assess lower extremity pulses (femoral, popliteal, dorsalis pedis, posterior tibial) and look for signs of arterial insufficiency before considering any compression therapy, as this is critical to avoid tissue necrosis. 1, 2

Initial Clinical Assessment

History - Key Elements to Elicit

• Unilateral vs. bilateral swelling: Unilateral suggests venous thrombosis, venous insufficiency, or lymphedema; bilateral typically indicates systemic disease (heart failure, renal/hepatic disease, hypoproteinemia) 3, 4, 5

• Acute vs. chronic onset: Sudden unilateral swelling raises concern for deep venous thrombosis (DVT) and requires urgent evaluation 2, 6

• Associated symptoms: 1

  • Pain quality and timing (rest vs. exertional, relief with elevation)
  • Skin changes (erythema, warmth, hyperpigmentation, ulceration)
  • Heaviness, fatigue, cramping (especially at night)
  • Symptoms worsening by end of day or with prolonged standing/walking

• Risk factors for arterial disease: Age ≥65 years, diabetes, smoking history, hypertension, dyslipidemia, known atherosclerotic disease elsewhere 1

• Risk factors for venous disease: Prior DVT, prolonged immobility, recent surgery, malignancy, hypercoagulable states 1, 6

Physical Examination - Specific Findings to Document

Vascular examination (remove all lower extremity garments, shoes, and socks): 1, 2

• Pulse assessment: Palpate and grade bilaterally (0=absent, 1=diminished, 2=normal, 3=bounding) at femoral, popliteal, dorsalis pedis, and posterior tibial sites 1

  • Presence of all four pedal pulses bilaterally suggests low likelihood of peripheral artery disease 2

• Signs of arterial insufficiency: 1, 2

  • Vascular bruits (femoral, popliteal)
  • Asymmetric hair growth
  • Nail bed changes
  • Calf muscle atrophy
  • Elevation pallor or dependent rubor
  • Nonhealing wounds or gangrene

• Signs of venous insufficiency: 1, 6

  • Dependent pitting edema
  • Hemosiderin deposition (brownish discoloration)
  • Varicose veins
  • Lipodermatosclerosis
  • Venous ulceration (typically medial malleolus)
  • Stasis dermatitis

• Signs of lymphedema: 6

  • Brawny, nonpitting edema
  • Skin thickening
  • Stemmer sign (inability to pinch skin at base of second toe)

• Popliteal fossa examination: Palpate for Baker's cyst (swelling and tenderness behind knee, may worsen with exercise) 7

Diagnostic Testing Algorithm

First-Line Testing

If acute unilateral swelling (concern for DVT): 2, 6

• Venous duplex ultrasound immediately to evaluate for deep venous thrombosis
• If positive, initiate anticoagulation per established guidelines (minimum 3 months for proximal DVT) 2

If abnormal pulse examination or signs of arterial insufficiency: 1

• Ankle-brachial index (ABI) to establish diagnosis of peripheral artery disease
• ABI 0.6-0.9 requires adjusted compression pressure; <0.6 contraindicates compression therapy 2
• If ABI abnormal or high clinical suspicion, refer to vascular surgery 2

If chronic bilateral swelling without obvious cause: 3, 6

• Basic laboratory workup: Complete blood count, comprehensive metabolic panel, liver function tests, albumin, thyroid-stimulating hormone, urinalysis
• Brain natriuretic peptide if heart failure suspected
• Consider echocardiography if cardiac etiology suspected

Advanced Imaging (When Indicated)

For suspected Baker's cyst: 7

• Ultrasound is preferred initial diagnostic tool (comparable accuracy to MRI for confirming popliteal cyst, can detect rupture)
• Plain radiographs of knee (AP, lateral, sunrise, tunnel views) to evaluate underlying joint pathology
• MRI without contrast if additional evaluation needed or concomitant internal knee pathology suspected

For suspected lymphedema: 6

• Clinical diagnosis primarily; imaging rarely needed
• Evaluate for secondary causes: history of malignancy, pelvic surgery, radiation, lymphadenectomy

For venous insufficiency with unclear etiology: 1

• Venous duplex ultrasound to assess for valvular incompetence and residual obstruction
• Consider magnetic resonance venography if duplex negative but high clinical suspicion for pelvic/proximal venous thrombosis

Critical Safety Considerations

Never apply compression therapy without first ruling out arterial insufficiency - this can cause tissue necrosis and limb loss. 2 Check pulses and consider ABI before any compression recommendations. 1, 2

Immediate vascular surgery consultation required for: 2

• Nonhealing wounds with arterial insufficiency
• Lower extremity gangrene
• Signs of acute limb ischemia (pain, pallor, pulselessness, poikilothermia, paresthesias, paralysis) 1

Common Diagnostic Pitfalls

• Assuming bilateral swelling is always systemic: Consider bilateral venous insufficiency or lymphedema 3, 5

• Missing ruptured Baker's cyst: Can mimic DVT with acute calf pain and swelling; ultrasound differentiates 7

• Overlooking lipedema: Bilateral symmetric adipose deposition sparing feet, often misdiagnosed as obesity or lymphedema 8

• Failing to examine for wounds: In diabetic or arterial disease patients, inspect between toes and plantar surfaces for ulceration 1

• Not recognizing venous claudication: Bursting leg pain during exercise from venous obstruction can resemble arterial claudication 1