What is Fournier's gangrene?

Fournier's Gangrene: A Life-Threatening Necrotizing Infection

Fournier's gangrene is a rare but potentially fatal necrotizing fasciitis of the perineal, genital, or perianal region characterized by rapidly progressive infection of the fascia and subcutaneous tissues with high mortality rates of 20-50% if not promptly diagnosed and treated. 1

Definition and Epidemiology

• Defined as "an infective necrotizing fasciitis of the perineal, genital, or perianal region" 1
• Incidence: approximately 1.6 cases per 100,000 males annually in the USA 1
• Demographics:
  • Strong male predominance (male to female ratio of 42:1) 1
  • Mean age of presentation: 51 years 1
  • Mortality rates: 7.5-88% depending on studies 1

Pathophysiology

The disease progression follows a specific pattern:

1. Initial localized infection allows entry of bacteria into the perineum
2. Inflammatory response causes obliterative endarteritis and vessel thrombosis
3. Reduced blood flow leads to tissue ischemia
4. Anaerobic bacteria proliferation accelerates fascial necrosis and tissue digestion 1

The infection typically spreads rapidly along fascial planes:

• Cranially to the abdominal wall
• Caudally to the legs
• Following superficial perineal fascia (continuous with Colles' fascia and Scarpa's fascia) 1

Etiology

Sources of infection include:

• Perineal skin (24%)
• Colorectal region (21%)
• Genitourinary tract (19%)
• Unknown origin (36%) 1

Microbiology:

• Typically polymicrobial (average of 5 pathogens)
• Common organisms: Streptococcus, Staphylococcus, Escherichia coli 1, 2
• Recent emergence of community-acquired MRSA in some cases 3
• Rarely fungal etiology (Candida spp. or molds) 3

Risk Factors

Major predisposing conditions:

• Diabetes mellitus (most common, present in 51.2% of cases) 1, 4
• Obesity 1, 5
• Immunocompromised states 1
• Alcoholism 1, 4
• Vascular insufficiency 2
• Cirrhosis of the liver 4
• Uremia 4
• Underlying malignancy 4

Clinical Presentation

Key clinical features:

• Intense perineal and/or scrotal pain (often disproportionate to physical findings) 1, 6
• Swelling and erythema of affected areas 1
• Systemic features: fever (87.8%), tachycardia 1, 4
• Disease progression signs:
  • Purulent discharge
  • Crepitus (subcutaneous emphysema)
  • Patches of necrotic tissue with surrounding edema
  • Cutaneous gangrene (appears later in disease course) 1

Diagnosis

Diagnosis is primarily clinical:

• Focused medical history and complete physical examination including digital rectal examination 1
• Laboratory studies for suspected cases with systemic infection/sepsis:
  • Complete blood count
  • Serum creatinine and electrolytes
  • Inflammatory markers (C-reactive protein, procalcitonin)
  • Blood gas analysis
  • Serum glucose, hemoglobin A1c, and urine ketones (to investigate undetected diabetes) 1

Prognostic scoring systems:

• Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC): for early diagnosis
• Fournier's Gangrene Severity Index (FGSI): for prognosis and risk stratification
  • FGSI score above 9 is sensitive and specific as a mortality predictor 1

Imaging may help confirm clinical suspicions and identify extent of involvement:

• Conventional radiology, ultrasound, CT, and MRI 1

Treatment

Treatment requires a multidisciplinary approach with several critical components:

1. Early and aggressive surgical debridement is the cornerstone of treatment and significantly improves survival 1

   • Radical surgical debridement of all affected tissue, extending into healthy-looking tissue
   • Multiple debridements are often necessary
   • Cultures should be obtained during initial debridement 1

2. Prompt broad-spectrum antibiotic therapy 1, 5

   • Coverage for aerobic and anaerobic organisms
   • High doses to reach effective concentration in infected tissues 3

3. Hemodynamic support and resuscitation 1, 5

   • Aggressive fluid resuscitation
   • Management of septic shock if present

4. Additional interventions to consider:

   • Fecal diversion (colostomy or fecal tube system) in cases with fecal contamination 1
   • Negative pressure wound therapy (NPWT) after complete removal of necrosis 1, 5
   • Reconstructive surgery for wound coverage after infection control 4

Prognosis and Monitoring

• Procalcitonin (PCT) ratio monitoring can help assess successful surgical intervention
  • PCT ratio of postoperative day 1 to day 2 > 1.14 indicates successful surgical treatment 1

Key Pitfalls to Avoid

1. Delayed diagnosis - Early recognition is critical as delayed debridement significantly worsens survival rates 4, 6
2. Misdiagnosis as simple cellulitis - FG can initially present with symptoms similar to cellulitis 6
3. Inadequate surgical debridement - Must be aggressive and extend into healthy tissue 1
4. Underestimating disease in female patients - Though less common, FG in women may be underrecognized 3
5. Failure to investigate for underlying diabetes - Undiagnosed diabetes is a common finding 1