Table Of Contents
Fournier’s Gangrene
Fournier’s Gangrene is necrotising fasciitis of the perineum and external genitalia that can spread rapidly to the anterior abdominal wall (Meleney gangrene) and gluteal muscles. Urogenital causes of Fournier’s gangrene begin with necrosis of the anterior triangle, while anorectal causes begin with necrosis of the posterior triangle. Fascia that are affected include the colles, dartos, bucks, Scarpa’s and camper’s fascia.
Fournier’s gangrene is more common in elderly men, women, children, diabetics and immunocompromised. It is common between 30 – 60 years of age.
- Common ausative organisms
- Mixed infection
- Facultative pathogens: Escherichia coli, Peptostreptococcus spp. , Enterococcus
- Anaerobes: Bacteroides fragilis, Fusobacterium, Clostridium perfringens
- Risk factors for Fournier’s gangrene
- Local trauma
- Instrumentation to the perineum
- Circumcision
- Episiotomy
- Extravasation of urine (periurethrally OR via cutaneous fistulas)
- Hernioplasty
- Hysterectomy
- Paraphimosis
- Septic abortion
- Urethral stricture caused by STDs
- Scrotal abscess
- Immunosuppression: diabetes mellitus, alcohol use, steroids, chemotherapy, HIV
- Fascial planes affected in Fournier’s gangrene
- Colle’s fascia: Fascia of the anterior triangle of the perineum (limits the posterior spread of the infection as it merges with the posterior edge of the perineal membrane)
- Dartos fascia: Continuation of Colle’s fascia over the scrotum
- Buck’s fascia: Deep fascia covering the corpus spongiosum and corpus cavernosa of the penis
- Scarpa’s fascia: Deep fascia of the abdomen
- Camper’s fascia: Superficial fascia of the abdomen
- Pathophysiology
- Poor host defense due to underlying predisposing factors → Polymicrobial infection → Vascular thrombosis and tissue necrosis
- Pathogenesis of intravascular coagulation:
- Aerobes → platelet aggregation and complement fixation
- Anerobes → heparinase
- Hypoxia → Free oxygen radicals → cell membrane damage, decreased ATP, DNA damage, Decreased protein synthesis
- Spread
- It spreads to contiguous areas but occasionally also produces skip lesions that later coalesce.
- Spread is usually from the perineum towards the abdomen
- Why does scrotal skin die while testes remain intact?
- Necrotizing soft tissue infections are associated with vascular thrombosis and tissue necrosis. The testes remain intact since they have a separate blood supply from scrotal skin
- The scrotum receives blood from the external pudendal arteries whereas the testes are supplied by testicular arteries which arise directly from the abdominal aorta.
- Pathogenesis of tissue necrosis:
- Exotoxins, Lecithinase, Collagenase, Hyaluronidase → digestion of fascial planes → insoluble hydrogen, nitrogen, methane, CO2 that produces palpable crepitus
- Pathogenesis of shock:
- Endotoxin → Complement, TNF, IL-1 → Septic shock
- How does Fournier’s gangrene spread?
- It spreads to contiguous areas but occasionally also produces skip lesions that later coalesce.
- Usually from the perineum towards the abdomen
- Signs and symptoms
- Pruritus and discomfort of the genitalia
- Severe pain
- Redness and tenderness
- Crepitus (due to methan and CO2 production)
- Loss of sensation of the affected area
- Purple skin discoloration (necrosis and ecchymosis)
- Bullae
- Purulent discharge (greyish dishwater fluid)
- Foul smell (very characteristic of necrotizing fasciiitis)
- Fever and lethargy (may occur days before the onset of gangrene)
- Altered mental status)
- Differentials
- Cellulitis
- Strangulated hernia
- Testicular torsion
- Scrotal absces
- Vascular occlusion syndromes
- Herpes simplex
- Gonococcal balanitis and oedema
- Pyoderma gangrenosum
- Allergic vasculitis
- Necrolytic migratory erythema
- Investigations
- X-ray of the pelvis: imagign is not routine and should not delay treatment.
- Gas in soft tissue (absence does not rule out NSTI)
- CBC
- Leukocytosis
- Urea, electrolytes and creatinine: renal funciton may be compromised
- CRP
- Elevated
- ESR
- Elevated
- Pro-calcitonin
- Elevated
- Random blood sugar
- Hyperglycaemia may be present due to diabetes or as a systemic response to inflammation
- Blood culture: possibly for the causative organism
- Deep tissue gram stain and culture: will guide antibiotic treatment
- X-ray of the pelvis: imagign is not routine and should not delay treatment.
- Treatment
- Admit (this is a surgical emergency)
- Resuscitation
- Broad-spectrum coverage antibiotics
- Wide surgical debridement
- Fecal diversion (colostomy)
- Urinary diversion (per-urethral foley catheter if possible)
- Reconstruction
- Factors associated with high mortality (poor prognosis)
- Anorectal origin
- Advanced age
- Extensive disease
- Shock
- Sepsis at presentation
- Renal failure
- Hepatic dysfunction
- Complications of Fournier’s gangrene
- Sepsis
- Septic shock
- Disseminated intravascular coagulopathy
- Multi-organ system dysfunction (MODS)
- Death
