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Necrotizing Fasciitis

General Considerations

  • A rapidly progressive, infection of fascia which leads to subsequent necrosis of the subcutaneous tissue; muscles are frequently spared
  • It may be caused by several organisms of groups of organisms
    • Type 1: Polymicrobial
      • Bacteroides, Clostridium, or Peptostreptococcus) in combination with streptococci other than group A and E. coli, Enterobacter, Klebsiella or Proteus
    • Type 2: Group A beta-hemolytic streptococcus
    • Clostridial infections (gas gangrene)
  • Frequency may be increasing because of immunocompromised patients
  • Organisms spread from subcutaneous tissue along both superficial and deep fascial planes
    • Spread may be aided by bacterial enzymes and toxins.
  • Carbon dioxide, hydrogen, nitrogen, hydrogen sulfide, and methane are produced from aerobic and anaerobic metabolism and lead to the presence of gas in the soft tissues

Clinical Findings

  • Intense pain, sometimes out of proportion to the physical findings, and tenderness over involved area
  • After a few days, nerve necrosis may produce anesthesia in the area, a clue to the presence of necrotizing fasciitis
  • Edema, skin vesicular eruptions and crepitus
  • Lymphangitis and lymphadenitis are infrequent
  • Fever, malaise
  • Surgical exploration is the only way to definitively establish the diagnosis of necrotizing infection and distinguish it from other entities

Imaging Findings

  • Plain films are insensitive to the presence of gas in the soft tissues so that a negative conventional radiograph should not rule out the diagnosis
  • Non-enhanced CT is the study of choice and may show thickening of fascial planes and gas in the subcutaneous tissue
    • Gas is seen most often in Type 1 and that caused by Clostridium
    • CT is specific but not highly sensitive
    • In the absence of gas, surgical exploration is necessary
  • MRI can be sensitive in determining the presence of necrosis and need for surgical debridement, combined with clinical evaluation
  • Ultrasound may reveal subcutaneous collections of air and fluid not otherwise seen

Differential Diagnosis

  • Cellulitis


  • Of all patients with necrotizing fasciitis about 20-40% are diabetic
  • May be seen in association with cardiac catheterization
  • Vein sclerotherapy
  • Diagnostic laparoscopy
  • Possible association with non-steroidal anti-inflammatory drugs
  • May be idiopathic, as in scrotal or penile necrotizing fasciitis (Fournier Gangrene)


  • Surgical emergency involving debridement of the affected areas
  • Aggressive antibiotic therapy
  • Hyperbaric oxygen treatment may be helpful


  • Mortality rates from 20% to 80% have been reported
  • Factors which affect prognosis include
    • Pathogens
    • Complicating diseases
    • Infection site
    • Rapidity with which treatment is instituted

Necrotizing Fasciitis

Necrotizing Fasciitis

Necrotizing Fasciitis. Upper:Lateral radiograph of foot showing soft tissue swelling over the dorsum of the foot with gas in the soft tissues (white oval). Bottom:Axial CT of same foot with gas bubbles seen throughout the soft tissues (yellow oval).
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Necrotizing Soft Tissue Infections. Up-to-Date. Dennis L Stevens, and Larry M Baddour