Necrotising Fasciitis

A rapidly spreading infection of fascia and subcutaneous tissue with secondary skin necrosis. Mortality is high and depends almost entirely on time to surgical debridement. The defining trap is that the skin looks better than the patient is: early…

Surgical Emergency — Pain Out of Proportion

The pathway

1 · Recognise — and what separates it from cellulitis

The discriminators, in order of usefulness:

Pain out of proportion to the skin appearance — severe pain in a limb that looks mildly cellulitic
Rapid progression over hours; mark the margin and re-examine
Systemic toxicity disproportionate to a skin infection — tachycardia, hypotension, confusion
Anaesthesia over the affected skin (cutaneous nerves infarct)
Crepitus, dusky or bruised discolouration, haemorrhagic blisters, skin necrosis — these are late

Risk factors: diabetes, immunosuppression, injecting drug use, recent surgery, chickenpox in children, peripheral vascular disease. It also occurs in previously well people after trivial trauma.

2 · Call the surgeons — before the investigations

If you are considering the diagnosis, telephone the surgical registrar now. Not after the bloods, not after imaging, not after the antibiotics are running.

This is the whole pathway. Every other step below happens in parallel with that call, not before it. Delay to debridement is the single strongest predictor of death.

Site determines the team: general/plastic surgery for trunk and limbs, urology for Fournier's gangrene, ENT/maxfax for cervical involvement.

3 · Resuscitate as sepsis

Sepsis 6 — this is severe sepsis and should be treated as such
Large-bore access, aggressive fluid resuscitation, catheter, lactate
Blood cultures before antibiotics if it does not delay them
Broad-spectrum antibiotics per local policy — typically covering Gram-positives, Gram-negatives and anaerobes, with an agent to suppress toxin production added on microbiology advice
Discuss with microbiology urgently
Group and save, clotting — these patients go to theatre

4 · Investigations — supportive, never exclusionary

Bloods: FBC, U&E, CRP, LFT, glucose, lactate, clotting, CK, group & save
LRINEC uses CRP, WCC, Hb, sodium, creatinine and glucose
A low score does not exclude it. Using it to reassure yourself is a documented route to a missed diagnosis
Imaging must not delay surgery. CT may show fascial gas or fluid tracking, but a normal CT does not exclude it

The diagnosis is made in theatre, on the appearance of the fascia — greyish, non-bleeding, separating from muscle with minimal resistance ('finger test').

5 · Definitive treatment

Radical surgical debridement of all non-viable tissue, back to bleeding tissue
Planned re-look in 24–48 hours is the norm; several debridements are common
ITU post-operatively for most patients
IVIG is used in some centres for streptococcal toxic shock — a specialist decision
Reconstruction, and sometimes amputation, comes later

Drugs

Drug	Dose	Route	Notes
Broad-spectrum antibiotics	Per local policy	IV	Local antimicrobial guidance governs this. Needs Gram-positive, Gram-negative and anaerobic cover. Discuss with microbiology urgently.
Clindamycin	Per local policy	IV	Frequently added on microbiology advice for its anti-toxin effect in streptococcal infection. Not a substitute for debridement.
IV crystalloid	500ml boluses	IV	Reassess after each. Requirements are often very large.
Morphine	Titrated	IV	The pain is severe and is itself a diagnostic feature — treat it, and note how much is needed.

When to escalate

Any suspicion at all — surgical registrar immediately, before imaging or bloods,Fournier's gangrene (perineal/genital) — urology emergency,Septic shock — ITU alongside surgery, not after it,Cellulitis not responding to appropriate IV antibiotics — re-examine and reconsider this diagnosis,Skin necrosis, crepitus or bullae — late signs, escalate as an emergency

Reference: Written against general UK surgical and critical care practice. NICE NG141 covers cellulitis and erysipelas but not necrotising infection. Follow local surgical and antimicrobial protocols.

This page is the reference half

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