Diagnosis

The diagnosis of necrotising fasciitis is overridingly clinical. There must be low threshold for diagnosis if the following features are present:

• skin changes:
  • erythema
  • low-grade cellulitis
  • cyanotic discolouration or ecchymosis
  • epidermolysis or bullae
  • skin necrosis
  • anaesthesia of skin beyond the margin of surface colour change
  • crepitus
• a hard, indurated feel to the subcutaneous tissue which is present beyond the visible limits of skin involvement
• pain out of proportion to the visible surface changes
• signs of systemic toxicity with altered mental status, fever, shock or acute renal failure
• minimal improvement despite initial antibiotic therapy

A number of blood investigations may support the diagnosis. Imaging should not delay the patient progressing to theatre for rapid, adequate debridement.

Reference:

• 1. Hasham S et al. Necrotising fasciitis. BMJ 2005; 330(7495): 830-833
• 2. Stevens D.L et al. Practice Guidelines for the Diagnosis and management of Skin and Soft-Tissue Infections. CID 2005; 41:1373-406