Editing Necrotizing fasciitis (section)

==== Point-of-care ultrasonography (POCUS) ====
[[File:UOTW 58 - Ultrasound of the Week 1.webm|thumb|Necrotizing fasciitis as seen on ultrasound<ref>{{cite web |date=7 September 2015 |title=UOTW#58 – Ultrasound of the Week |url=https://www.ultrasoundoftheweek.com/uotw-58/ |url-status=live |archive-url=https://web.archive.org/web/20160718055845/http://www.ultrasoundoftheweek.com/uotw-58/ |archive-date=18 July 2016 |access-date=27 May 2017 |website=Ultrasound of the Week}}</ref>]]
[[File:Necrotizing fasciitis with soft tissue gas NF.webp|thumb|Necrotizing fasciitis with soft tissue gas seen on (b) plain radiography and (c) ultrasound]]
[[Emergency ultrasound|Point-of-care ultrasound]] (POCUS) may be useful in the diagnosis of NF if MRI and CT are not available.<ref name=":1">{{Cite journal |last1=Gan |first1=Rick Kye |last2=Sanchez Martinez |first2=Antoni |last3=Abu Hasan |first3=Muhammad Abdus-Syakur |last4=Castro Delgado |first4=Rafael |last5=Arcos González |first5=Pedro |date=2023-06-01 |title=Point-of-care ultrasonography in diagnosing necrotizing fasciitis—a literature review |journal=Journal of Ultrasound |language=en |volume=26 |issue=2 |pages=343–353 |doi=10.1007/s40477-022-00761-5 |issn=1876-7931 |pmc=10247625 |pmid=36694072}}</ref> It can also help rule out diagnoses that mimic earlier stages of NF, including [[Deep vein thrombosis|deep vein thrombosis (DVT)]], superficial abscesses, and [[venous stasis]].<ref name=":1" /> Linear probes are generally preferred for the assessment, especially in the extremities.<ref name=":1" />

Findings characteristic of NF include abnormal thickening, air, or fluid in the [[subcutaneous tissue]].<ref name=":1" /> This can be summarized as the mnemonic "STAFF" (Subcutaneous irregularity or Thickening, Air, and Fascial Fluid).<ref name=":1" /> The official diagnosis of NF using ultrasound requires "the presence of BOTH diffuse subcutaneous thickening AND fascial fluid more than 2 mm."<ref name=":1" /> Gas in the subcutaneous tissue may show "dirty acoustic shadowing."<ref name=":0" /> However, similar to other imaging modalities, the absence of subcutaneous free air does not definitively rule out a diagnosis of NF, because this is a finding that often emerges later in the disease process.<ref name=":1" />

Of note, the quality and accuracy of POCUS is highly user-dependent.  It may also be difficult to visualize NF over larger areas, or if there are many intervening layers of fat or muscle.  It is still unclear whether POCUS improves the speed of diagnosis of NF, or if it reduces the time to surgical intervention as a whole.<ref name=":1" />