Differential diagnosis

Think about other causes of unilateral leg swelling.  Common causes include ^a 

• cellulitis
• muscle injury
• superficial thrombosis

• chronic oedema or venous insufficiency 
• pelvic tumours compressing lymphatic or venous drainage 
• a ruptured Baker's cyst 
  • Look for ^a  
    • crepitus on flexing the knee
    • a history of arthritis
    • a positive ultrasound scan