Necrotising soft-tissue infection

Diagnosis begins with tempo. Ask when pain started, how quickly the boundary changed, recent trauma, injection, operation, bite, water or soil exposure, ulcers and previous antibiotics. Establish diabetes, immunosuppression, renal or liver disease, vascular disease and anticoagulation, but do not require a risk factor. Examine beyond the coloured area, comparing temperature, induration, tenderness and sensation. Mark and time the skin boundary only if doing so does not create false reassurance or delay theatre.

Early skin may show only erythema or swelling. Disproportionate deep pain, tenderness beyond visible change and a wooden fascial feel are more concerning than crepitus, bullae, dusky necrosis and anaesthesia, which often appear later. Examine perfusion, compartments, joints and the entire limb and girdle because infection can cross regions. Fournier disease needs perineal and abdominal source assessment; cervical disease needs airway planning. A painless area can mean nerve and tissue death rather than recovery.

Treat physiology and source in parallel. Apply the current adult sepsis pathway, obtain blood cultures when this does not delay antibiotics and give oxygen for a clinical indication. Use balanced isotonic crystalloid in measured two-hundred-and-fifty-millilitre boluses over ten to fifteen minutes with reassessment, generally not exceeding one litre before senior critical-care review. Start broad-spectrum intravenous therapy under the local necrotising-infection protocol and immediate microbiology advice, accounting for allergy, renal function, water or soil exposure and prior colonisation.

Imaging is subordinate to surgery. Plain films or CT may show gas, fascial fluid or an underlying foreign body, and ultrasound can locate an abscess, but absence of gas is common and no scan excludes early necrosis. Use cross-sectional imaging only when diagnosis is genuinely uncertain, the patient is stable and it will not defer exploration. The same principle applies to transfer: bring the required surgeons to the patient or operate for source control when transfer would create unsafe delay.

Index debridement confirms, maps and excises disease. Incise generously along the affected plane and inspect skin, fat, fascia, named vessels and nerves and all muscle groups. Non-adherent fascia, thrombosed vessels, fixed staining, haemorrhagic bullae, thin fluid and non-contractile muscle support the diagnosis, but absence of one classic sign does not clear tissue. BOASt describes zone 1 as obvious necrosis, zone 2 as likely infection and zone 3 as normal; remove zones 1 and 2 with a three-centimetre zone-3 cuff.

Sampling must preserve microbiological value. Take about five deep specimens across different zones with a new sterile instrument and no-touch technique for each. Label the anatomical site and mark the normal-zone sample separately, alert the laboratory and request microscopy and culture. Blood cultures supplement rather than replace tissue. Histology can assist at a viable margin but should never delay sufficient excision. Avoid relying on a superficial swab, which samples colonisation and not the advancing fascia.

Leave the wound open and document with diagrams or governance-compliant photographs. The treating team reviews the patient within six hours of diagnosis or surgery. Worsening shock, pain, skin change or laboratory trajectory means incomplete source control until proven otherwise and demands repeat exploration. Planned re-look often finds evolving viability even when physiology improves. Plastic and reconstructive surgeons plan negative-pressure therapy, grafts or flaps only after all infected tissue is removed.

Amputation can be life-saving but is not a single-operator decision. At least two consultants from relevant specialties document why excision cannot control disease while preserving a viable limb. Continue analgesia, organ support, nutrition, glucose control and thrombosis prevention around repeat operations. Later care addresses scar and contracture, prosthetics if needed, neuropathic and phantom pain, psychological trauma, return to function and public-health advice when invasive group A streptococcal disease affects close contacts.