Point-of-care ultrasound diagnosis of necrotizing fasciitis missed by computed tomography and magnetic resonance imaging.

BACKGROUND: Necrotizing fasciitis (NF) is a rare but deadly disease. Diagnosis of necrotizing soft tissue infections can be challenging for a variety of reasons. Point-of-care (POC) ultrasound (US) has been described as a diagnostic tool to help the acute care clinician make the early diagnosis that is imperative to optimize outcomes.
OBJECTIVE: To report a case of Group A Streptococcus NF recognized with POC US, and subsequent negative findings on computed tomography (CT) and magnetic resonance imaging (MRI). CASE REPORT: A 54-year-old diabetic woman presented to the Emergency Department with atraumatic right foot and lower leg pain associated with fever. Examination was concerning for NF, and a POC US was performed, which showed thickened deep fascia and fluid tracking along the deep fascial plane, with fluid pockets measuring 6 mm in depth, consistent with NF. Surgical consultation was obtained. Per request, CT and MRI of the patient's lower extremity were performed; both were interpreted by the radiologist as showing changes consistent with cellulitis. Septic shock and multisystem organ failure ensued; the patient was eventually taken to the operating room, where operative findings were consistent with NF. Operative cultures grew Streptococcus pyogenes.
CONCLUSION: NF is a surgical emergency. Early and accurate diagnosis is critical to ensure the necessary aggressive management needed to optimize outcomes. This case illustrates the utility of POC US to make the prompt diagnosis of NF, particularly in light of subsequently negative CT and MRI.