6th July 2023

Necrotising Fasciitis

A life-threatening soft tissue and fascia infection that leads to tissue necrosis. 50% of cases occur in previously healthy individuals. Predisposing risk factors include skin injury, chronic conditions (e.g. diabetes, renal disease), IV drug abuse and immunosuppression. It is caused by a mixture of aerobic and anaerobic organisms. This can be categorised into 4 main types, shown in table 2:

Table 2: Different categories of necrotising fasciitis

The primary feature of necrotising fasciitis is intense pain disproportionate to the clinical findings. The affected tissue is hot and swollen, with ill-defined erythema that rapidly becomes blackened and bullous. Subcutaneous crepitus develops from the accumulation of gas within the soft tissue.

Extensive necrotising fasciitis of the left leg 

Image Source: Wikimedia Commons (2009). Necrotizing fasciitis left leg, Licensed under a creative commons licence. Available for free at: https://en.wikipedia.org/wiki/File:Necrotizing_fasciitis_left_leg.JPEG (Accessed on: 10 March 2022).

A high index of suspicion is required for diagnosis. This is supported by raised inflammatory markers on blood tests and the presence of gas in the subcutaneous tissue on imaging such as x-ray or CT. Wound MCS and blood cultures should also be taken. Diagnosis is confirmed during surgical exploration with the presence of friable superficial fascia and grey exudate. Survival is improved with immediate surgical debridement. Supportive measures include broad-spectrum intravenous antibiotics, resuscitation and management in an intensive care setting.