title: A Necrotizing Fasciitis Fake Out on Point-of-Care Ultrasound-Watch the Shadow.
abstract: BACKGROUND
  Point-of-care ultrasound has an increasing role in characterizing soft-tissue infections and has been described previously in the evaluation of necrotizing fasciitis (NF). The identification of air within the soft tissues can be very suggestive of NF in the correct clinical context.
  
  
  METHODS
  A 78-year-old male presented to the emergency department with extensive lower-extremity redness and edema. A point-of-care ultrasound revealed hyperechoic areas within the soft tissues consistent with air, and the patient was taken to surgery and found to have NF. A 60-year-old female presented to the emergency department with physical examination findings consistent with severe cellulitis and associated sepsis. A point-of-care ultrasound revealed hyperechoic areas within the soft tissue that were very similar to the prior case. An emergent surgical consultation was placed due to concern for soft-tissue air and NF. However, these hyperechoic areas were found to be subcutaneous calcifications on subsequent imaging. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Air within the soft tissue is easy to identify on point-of-care ultrasound and can expedite surgical evaluation in cases of suspected NF. Calcifications can mimic the appearance of air on ultrasound and the distinction between these objects can often be made based on the echotexture of the posterior acoustic shadow. Attention to the posterior acoustic shadow can facilitate correct identification of various structures and pathologies in a variety of clinical settings.
authors.affiliation: University of Virginia Health System, Charlottesville, Virginia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Thom
authors.affiliation: University of Virginia Health System, Charlottesville, Virginia.
authors.forename: Mary
authors.initials: M
authors.lastname: Warlaumont
mesh_terms: D000368:Aged; D002113:Calcification, Physiologic / Q000502:physiology; D004636:Emergency Service, Hospital / Q000458:organization & administration; D005189:False Positive Reactions; D019115:Fasciitis, Necrotizing / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems / Q000592:standards*; D018461:Soft Tissue Infections / Q000175:diagnosis; D014463:Ultrasonography / Q000379:methods / Q000592:standards*
keywords: calcifications; necrotizing fasciitis; point of care ultrasound; posterior shadow; soft-tissue air; soft-tissue infection; ultrasound