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
- 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
- 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
- Gravitational
- Venous stasis
- Thrombophlebitis
- Lymphedema
- Medications
- Deep venous thrombosis (uncomplicated)
- Leg or foot infection
- 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
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