- Tenderness extending beyond the apparent involved area
- Indistinct margins of involvement
- Absence of lymphangitis (because the infection is in the deep fascia and not in the skin)
- Rapidly progressive despite the use of antibiotics
- If the patients looks too sick for cellulitis
- Bleb/Bullae, Crepitus (Though you cannot not rule out NF in their absence)
This is a great tool that can aid to diagnose cellulitis, NF or underlying collection/abscess.
- Variable appearance from anechoic to irregularly hyperechoic, internal echoes; may find hyper echoic sediment, septae or even gas!
- Posterior acoustic enhancement
- “Squish sign” with compression: ability to induce motion in the material with
- Necrotizing fasciitis:
- Marked thickening of the subcutaneous layer (i.e. cellulitis)
- Layer of anechoic fluid measuring >4mm, adjacent to the deep fascia
- Subcutaneous gas (acoustic shadowing and reverberation artifact) may be present
- Treat Sepsis (Fluids/Antibiotics)
- Remove the focus (Debridement/Amputation) - ASAP
- Always think NF whenever you call it cellulitis.
- Early NF may not show classical textbook skin changes.
- If you see bullae, feel crepitus - you are dealing with NF.
- Use POCUS (Point of Care USG) for soft tissue infections.
- Yen ZS, Wang HP, Ma HM, Chen SC, Chen WJ. Ultrasonographic screening of clinically-suspected necrotizing fasciitis. Acad Emerg Med 2002;9(12):1448-51.
- Chao HC, Lin SJ, Huang YC, Lin TY. Sonographic evaluation of cellulitis in children. J Ultrasound Med 2000;19(11):743-9.
- Tayal VS, Hasan N, Norton HJ, Tomaszewski CA. The effect of soft-tissueultrasound on the management of cellulitis in the emergency department. Acad Emerg Med 2006;13(4):384-8.
- Vincent LM. Ultrasound of soft tissue abnormalities of the extremities. Radiol Clin North Am 1988;26(1):131-44.
- Squire BT, Fox JC, Anderson C. ABSCESS: applied bedside sonography for convenient evaluation of superficial soft tissue infections. Acad Emerg Med 2005;12(7):601-6.