Everything You Ever wanted to Know About Necrotizing Fasciitis

Necrotizing fasciitis can present insidiously with nonspecific symptoms and minimal skin findings.

 Nec-Fasc Fast

This meta-analysis demonstrates that diagnosis of necrotizing fasciitis is difficult and the tools we have as Emergency Physicians do not have the best diagnostic accuracy to be able to rule out necrotizing fasciitis on their own given low sensitivities. CT scan looking for fascial edema or enhancement or gas appears to have the highest sensitivity of 94.3%. However, there is still room for error and a negative CT scan does not definitively exclude necrotizing fasciitis.

 Necrotizing Fasciitis and the Spectrum of Soft Tissue Infections

So, why might it be that the LRINEC score has not proven to be a robust and reliable indicator of necrotizing fasciitis? First, it is important to recognize what the components of LRINEC are really indicating – systemic derangement. These laboratory criteria are signatures of critical illness and severe sepsis. Early cases of necrotizing fasciitis may not yet demonstrate significant laboratory abnormalities, as patients’ disease has not yet progressed to that stage.

The LRINEC score

If high suspicion for necrotizing fasciitis through clinical history and physical exam, do not calculate a LRINEC score and go straight to operative debridement. Note: Use with caution, as the LRINEC Score has performed poorly in external validation, most recently in Neeki 2017.

Rare, But Can’t Miss: Necrotizing Fasciitis in the Pediatric Population

The diagnosis of necrotizing soft tissue infection is ultimately made upon visual examination of necrotic appearing tissue in the operating room. A general paucity of cutaneous findings early in disease progression can make diagnosis difficult,

Cellulitis vs Necrotizing Fasciitis

Consider necrotizing fasciitis in patients with concerning findings for serious soft tissue infections and risk factors. Purposefully attempt to rule out the condition by a careful examination and scrutiny of laboratory indicators.

Diagnosing Necrotizing Fasciitis

Diagnosis of NF can be particularly challenging as early signs can be difficult to distinguish from less harmful soft tissue infections such as cellulitis. It most often presents over the time course of hours and can lead to rapid tissue destruction, systemic illness, and death if not promptly recognized and intervened upon.

Intern Ultrasound of the Month: Necrotizing Fasciitis

Necrotizing infections are life-threatening, prompt recognition is key, and POCUS is a useful adjunct to clinical assessment, especially in unstable patients that you don't want to send out of the ED for imaging. It's generally a better rule in (than rule out) test but evidence is limited.

Necrotizing Fasciitis: Pearls & Pitfalls

Relying on the absence of skin necrosis, cutaneous anesthesia, gas formation, and bullae to rule out NF can be dangerous. Subcutaneous emphysema has been traditionally stressed as the classic finding of NF, but only gas-forming organisms produce this finding, and it is only present between 13-31% of the time.

Necrotizing Fasciitis: What We Have Learned

Unfortunately, due to the rarity of the disease as well as the fact that diagnosis is made in the operative theater, delay in diagnosis is common. These infections remain elusive, however, due to their relative rarity and similarity to other, more benign conditions.

What Is the Accuracy of Physical Examination, Imaging, and the LRINEC Score for the Diagnosis of Necrotizing Soft Tissue Infection?

Computed tomography (CT) has superior sensitivity compared with radiography for the diagnosis of necrotizing soft tissue infection, although different imaging findings have various diagnostic test characteristics. No single element of the physical examination, radiography, or the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score has sufficient sensitivity to exclude necrotizing soft tissue infection.