Bedside Focused Ultrasound in Necrotizing Fasciitis: The “Black-hole Sign”.
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Date
2014-01-21
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Abstract
Introduction: Necrotizing fasciitis (NF) is a life-threatening infection of soft tissues,
requiring prompt diagnosis and an aggressive management.
The role of ultrasonography (US) in emergency setting for early diagnosis of NF was
reported in literature, its accuracy being estimated 92% both before and without gas
production.
Presentation of the Case: A 65-year old man, with pulmonary metastasis from colonrectal
cancer, treated with chemotherapy, complained of dyspnoea, fever and a dull pain
in his left calf for 3 days. Skin was spared and no evidence of tactile alterations or edema
was found.
Bedside US focused on the painful zone revealed a small hypo-anechoic area in deep
subcutaneous tissue with blurred contours and posterior shadowing (“black-hole sign”),
referable to soft tissue necrosis. Thickness and hyperechogenicity of surrounding
subcutaneous tissue, due to diffuse inflammatory infiltrate and edema, and thin distal
fluid collection along the fascia, were also detected, without gas artifacts. Surgery
debridement was performed, tissue cultures yielding Escherichia Coli, maybe due to the
disruption of bowel mucosal wall.
Discussion and Conclusion: Bedside goal-directed US performed by emergency
physician can exclude alternative aetiologies to NF in severe localized pain of the lower
extremity. The depiction of blurred focal changes in the soft tissue, configuring an US “black-hole sign” and referable to fat necrosis and suppurative infiltration, may represent
the main early finding of NF, especially in the idiopathic form. Its identification should
alarm physicians, inducing further investigations and close monitoring. The employment
of bedside goal-directed US should be stressed in Emergency Department.
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Keywords
Necrotizing fasciitis, ultrasound in soft tissue, critical ultrasound, emergency ultrasound, gas gangrene
Citation
Testa A, Giannuzzi R, Silveri N Gentiloni. Bedside Focused Ultrasound in Necrotizing Fasciitis: The “Black-hole Sign”. British Journal of Medicine and Medical Research. 2014 Jan; 4(3): 898-904.