Necrotizing fasciitis

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Background

Risk Factors

  • DM
  • Drug use
  • Obesity
  • Immunosuppression
  • Recent surgery
  • Traumatic wounds

Clinical Features

  • Skin exam
Nectrotizing fasciitis
    • Erythema (without sharp margins)
    • Exquisitely tender (pain out of proportion to exam)
    • Skip lesions
    • Hemorrhagic bullae (violaceous bullae)
      • May be preceded by skin anesthesia (destruction of superficial nerves)
    • Crepitus (in type I infections)
  • Swelling/edema may produce compartment syndrome
  • Constitutional
    • Fever
    • Tachycardia
    • Systemic toxicity

Work-Up

  • CBC
  • Chem
  • PT/PTT/INR
  • CK
  • Lactate

Diagnosis

CT of necrotizing fasciitis
  • Surgical exploration is the ONLY way to definitively establish the diagnosis of necrotizing infection
  • Imaging
    • Should not delay surgical exploration
    • CT is study of choice

HUCLA NF vs Non-NF Criteria (Wall et al)

  • Retrospective study discovered:
    • WBC count >15.4(x103/mm3) OR Na <135(mmol/L)
    • Associated with NF and combo of both increased likelihood of NF
    • PPV 26%/NPV 99%
  • Good tool to R/O NF, not a good tool for confirming presence of NF
    • Helps distinguish NF from non-NF infection, when classic 'hard' signs of NF are absent

Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) Score (Wong et al)

  • May use to risk stratify patients p/w signs of cellulitis to determine likelihood of necrotizing fasciitis
  • Useful in context of a diagnosed or strongly suspected severe soft-tissue infxn
  • Score based on: CRP, WBC, Hb, Na, Cr, Glucose
  • Score > 6 has PPV of 92% and NPV of 96% for necrotizing fasciitis
    • Be aware LRINEC score has not been prospectively validated, index of suspicion is key
  1. CRP (mg/L) ≥150: 4 pts
  2. WBC count (x103/mm3):
    1. <15: 0 pts
    2. 15-25: 1 pt
    3. >25: 2 pts
  3. Hb (g/dL):
    1. >13.5: 0 pts
    2. 11-13.5: 1 pt
    3. <11: 2 pts
  4. Na (mmol/L) <135: 2 pts
  5. Cr (mg/dL) >1.6: 2 pts
  6. glucose (mg/dL) >180: 1 pt

Differential Diagnosis

Skin and Soft Tissue Infection

Look-A-Likes

Treatment

  • Surgical exploration and debridement
    • Indicated in setting of severe pain, toxicity, fever, elevated CK (w/ or w/o radiographic evidence)
  • Antibiotics

Disposition

Admit/OR

See Also

Source