What follows are excerpts from Resource (1) below, Diagnosis of Necrotizing Faciitis with Bedside Ultrasound: the STAFF Exam [PubMed Abstract] [Full Text HTML] [Full Text PDF]. West J Emerg Med. 2014 Feb;15(1):111-3. doi: 10.5811/westjem.2013.8.18303:
DISCUSSION
The diagnosis of necrotizing fasciitis is initially
suspected by clinical findings classically characterized by
erythema with ill-defined borders, rapid progression in size,
and association with severe pain and tenderness beyond the
apparent area of involvement.4,5Often, the early stage of necrotizing fasciitis is
clinically indistinguishable from soft tissue infections such
as cellulitis and erysipelas, making the early diagnosis
difficult.4,5 While more subtle, this presentation is associated
with a similar mortality if not treated by early aggressive
surgical debridement.1Diagnostic criteria have been developed due to frequent
ambiguity of the clinical diagnosis. These include the use of
decision rules (LRINEC score),9 CT, MRI, and ultrasound;
with CT and MRI being the mainstays of diagnosis in
ambiguous cases. While studies have shown that CT and MRI
provide a higher sensitivity and superior evaluation of disease
extent compared to ultrasound,10 these imaging modalities can
be time consuming, thus delaying definitive treatment.1,7The diagnostic ultrasound findings consistent with
necrotizing fasciitis include fascial and subcutaneous tissue
thickening, abnormal fluid accumulation in the deep fascia
layer, and, in advanced cases, subcutaneous air.6,8 These
criteria can be recalled using a proposed “STAFF” mnemonic. . . . However, while it is not recommended to exclude necrotizing fasciitis on the basis of ultrasound,3 it has been shown to be specific for soft tissue infections, with one study reporting sensitivity of 88% and specificity of 93% using ultrasound.8
The sensitivity of ultrasound varies depending on the location and extent of necrotizing fasciitis; current ultrasound technology is thus unable to safely rule out the diagnosis. Here, a case is presented where bedside ultrasound allowed providers to forgo time intensive tests such as CT or MRI, which would
have delayed definitive operative management in an unstable
patient with necrotizing fasciitis.
Resources
(1) Diagnosis of Necrotizing Faciitis with Bedside Ultrasound: the STAFF Exam [PubMed Abstract] [Full Text HTML] [Full Text PDF]. West J Emerg Med. 2014 Feb;15(1):111-3. doi: 10.5811/westjem.2013.8.18303.
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(2) Results Of A PubMed Search “imaging of necrotizing fasciitis”
A list of 458 articles was returned.
