Point-of-care ultrasound evaluation of lower extremity erythema.

CASE PRESENTATION

A 58‐year‐old male with a history of diabetes and hypertension was brought to the emergency department (ED) for evaluation of altered mental status. Upon arrival, the patient was ill appearing, encephalopathic, and with the following vital signs: temperature 37.2°C, blood pressure 121/89 mmHg, heart rate 168 beats/min, respiratory rate 28 breaths/min, and oxygen saturation 98% on a nonrebreather mask. Physical examination revealed extensive tenderness and erythema of the distal right lower extremity with associated ecchymosis and necrotic tissue of the medial‐plantar aspect of the right foot (Figure 1). Bedside soft tissue point‐of‐care ultrasound (POCUS) was subsequently performed, which demonstrated hyperechoic air foci with dirty posterior shadowing and perifascial fluid accumulation consistent with necrotizing fasciitis (Figure 2). Orthopedic surgery was immediately consulted based on the abnormal POCUS findings. The patient was further resuscitated with intravenous fluids and empiric antibiotics, and orthopedic surgery emergently brought the patient to the operating room for a right below‐knee amputation.

FIGURE 1

Physical examination of the distal right lower extremity revealing extensive erythema with ecchymosis and necrotic tissue of the medial‐plantar aspect of the right foot

FIGURE 2

Point‐of‐care ultrasound of the affected right tibia in a transverse (A) plane demonstrating perifascial fluid accumulation (between plus symbols). Point‐of‐care ultrasound of the affected right foot in transverse (B,C) and longitudinal (D) planes demonstrating hyperechoic air foci (arrows) with dirty posterior shadowing representative of necrotizing fasciitis. Subcutaneous edema (asterisks) clinically consistent with overlying cellulitis

DIAGNOSIS

Necrotizing fasciitis

Necrotizing fasciitis is a time‐sensitive, life‐threatening skin and soft tissue infection that necessitates early identification in the ED. , Clinical examination and plain radiography findings are poorly sensitive for detecting necrotizing fasciitis; therefore, prompt diagnosis is notoriously challenging. There is an emerging role for POCUS performed by emergency physicians as an alternative diagnostic modality for necrotizing fasciitis, with high sensitivity and specificity previously reported. , The sonographic features of necrotizing fasciitis may include the presence of the following: diffuse thickening of subcutaneous tissue, irregular fascial planes with perifascial fluid accumulation, and air foci with dirty posterior shadowing. , , , , Critically, POCUS was instrumental in our case to yielding a rapid diagnosis and expedited surgical management without obtaining further advanced gold standard imaging. This report highlights the decisive role of emergency physician‐performed POCUS ultrasound as a first‐line bedside screening tool in the ED diagnosis of necrotizing fasciitis.