Unilateral leg swelling

Background

• Unilateral leg swelling is a common ED complaint
• The critical EM concern is ruling out deep vein thrombosis (DVT), which can lead to pulmonary embolism
• Other important causes include cellulitis, compartment syndrome, ruptured Baker's cyst, and necrotizing fasciitis
• Further classified as pitting (compressible) and non-pitting (lymphedema, myxedema)

Causes of pedal edema

Mechanisms of Pedal Edema

• Increased hydrostatic pressure
• Decreased oncotic pressure
• Increased capillary permeability
• Lymphatic obstruction

Clinical Features

History

• Onset: acute (DVT, cellulitis, compartment syndrome) vs. chronic (venous insufficiency, lymphedema)
• Pain: DVT (calf tenderness), cellulitis (diffuse), compartment syndrome (severe, out of proportion)
• Skin changes: erythema, warmth, skin break, ulceration
• Recent surgery, immobilization, travel, hospitalization, malignancy (DVT risk factors)
• History of DVT/PE
• Fever (infection)
• Trauma (compartment syndrome, fracture)

Physical Exam

Pitting pedal edema

• Measure and compare calf circumferences (>3cm difference is significant)
• Assess for pitting vs. non-pitting edema
• Skin: erythema, warmth, crepitus, bullae, ecchymosis, skin breaks
• Palpate pulses (arterial disease)
• Assess compartments for firmness, pain with passive stretch (compartment syndrome)
• Homan sign (calf pain with dorsiflexion) — poor sensitivity and specificity, not reliable

Red Flags

• Compartment syndrome: pain out of proportion, tense swelling, pain with passive stretch, paresthesias
• Necrotizing fasciitis: pain out of proportion, crepitus, rapidly spreading erythema, systemic toxicity
• Phlegmasia cerulea dolens: massive DVT with cyanotic, severely swollen limb, risk of limb loss

Differential Diagnosis

Unilateral leg swelling

Differential Diagnosis of Pedal Edema

• Gravitational
• Venous stasis
• Thrombophlebitis
• Lymphedema
• Medications
  • NSAIDS
  • Birth control
  • Steroids
• Deep venous thrombosis (uncomplicated)
  • Phlegmasia alba dolens
  • Phlegmasia cerulea dolens
• Leg or foot infection
  • Cellulitis
  • Necrotizing fasciitis
  • Septic Joint
• Fracture
• Compartment syndrome
• Limb hypertrophy
  • Hypertrophy of soft tissue or bone (Klippel-Trenaunay syndrome)
  • Overgrowth of body part (Proteus Syndrome)
• Lipedema
• Tumor
• Post-thrombotic Syndrome
• Causes of bilateral pedal edema
  • CHF
  • Pretibial myxedema
  • Renal failure
  • Liver failure
  • Hypoalbuminemia

Evaluation

DVT Assessment

• Apply Wells criteria for DVT pretest probability
  • Low probability: obtain D-dimer; if negative, DVT effectively excluded
  • Moderate/high probability: proceed directly to compression ultrasound
• DVT ultrasound (compression ultrasound) is the diagnostic study of choice
  • Sensitivity >95% for proximal DVT
  • If negative but clinical suspicion remains high, consider repeat in 5-7 days or whole-leg ultrasound

Infection Assessment

• CBC with differential, BMP
• Blood cultures if systemic signs of infection or concern for bacteremia
• Lactate if concern for sepsis or necrotizing fasciitis
• Consider CT or MRI if deep space infection or abscess suspected
• X-ray if concern for gas in soft tissues (necrotizing fasciitis, gas gangrene)

Other

• Knee X-ray: if trauma or concern for fracture
• POCUS: assess for DVT at bedside, popliteal (Baker's) cyst
• Consider CT venography if ultrasound nondiagnostic and clinical suspicion high
• Compartment pressures if compartment syndrome suspected (or clinical diagnosis if classic findings)

Management

DVT

• Anticoagulation: see Deep vein thrombosis for detailed management
• Elevation, analgesia
• Emergent vascular surgery consultation for phlegmasia cerulea dolens (may need catheter-directed thrombolysis or thrombectomy)

Cellulitis

• Antibiotics based on severity (see Cellulitis)
• Outpatient oral antibiotics for uncomplicated
• IV antibiotics for systemic signs, failed outpatient therapy, or immunocompromised

Compartment Syndrome

• Emergent surgical consultation for fasciotomy
• Remove all constrictive dressings/casts
• Do not elevate above heart level

Necrotizing Fasciitis

• Emergent surgical debridement
• Broad-spectrum IV antibiotics
• See Necrotizing fasciitis

Baker's Cyst Rupture

• Conservative management: rest, elevation, NSAIDs, compression
• Must rule out DVT (can coexist)

Disposition

Admit

• Proximal DVT with hemodynamic compromise or phlegmasia
• Compartment syndrome (to OR)
• Necrotizing fasciitis (to OR)
• Cellulitis requiring IV antibiotics
• Sepsis from lower extremity source

Discharge

• Uncomplicated DVT: can be managed outpatient with anticoagulation if reliable patient and adequate follow-up
• Uncomplicated cellulitis responding to oral antibiotics
• Baker's cyst rupture with DVT excluded
• Chronic venous insufficiency: compression stockings, elevation, outpatient follow-up
• Return precautions: worsening swelling, increasing pain, shortness of breath or chest pain (PE concern), fever, skin color changes

See Also

• Deep vein thrombosis
• Bilateral leg swelling
• Cellulitis
• Compartment syndrome
• Necrotizing fasciitis

External Links

• DDxOf: Differential Diagnosis of Lower Extremity Edema