Fournier's gangrene

Overview

Fournier's gangrene is a rapidly progressive polymicrobial necrotising fasciitis of the perineum, scrotum, penis, vulva, and perianal region. Mortality 20-40%; early recognition and emergency debridement are life-saving.

Risk factors

Diabetes mellitus - most common

Obesity

Immunosuppression / HIV

Chronic alcohol use

Chronic renal failure

Haematological malignancy

Perianal abscess / anal fistula

Urethral stricture / indwelling catheter

Minor perineal trauma

Presentation

•Pain out of proportion to visible skin changes - single most important early clue

•Perineal erythema, swelling, induration - progressing to skin necrosis and gangrene

•Subcutaneous crepitus on palpation (gas-forming organisms)

•Systemic sepsis - fever, tachycardia, hypotension, rigors

•Skin can appear deceptively normal while fascia beneath is already necrotic

🚨

Pain out of proportion to skin findings + perineal erythema + sepsis = Fournier's gangrene until proven otherwise. Do not wait for visible necrosis - escalate urgently to surgery.

Investigations

•Investigations must not delay surgery - diagnosis is clinical and confirmed intraoperatively

•Bloods: FBC, U&E, CRP, glucose, clotting, blood cultures, lactate - identify sepsis, organ dysfunction, diabetes; used to calculate LRINEC score

•Plain X-ray pelvis/perineum: may show subcutaneous gas confirming gas-forming infection

•CT pelvis with contrast: delineates extent of fascial involvement and gas tracking along planes; use only if haemodynamically stable

•Wound swabs / operative tissue samples: MC&S to guide antibiotic rationalisation - results not awaited before empirical treatment

🏆 Gold standard

•surgical exploration - necrotic fascia that fails to bleed, 'dishwater' fluid, no resistance to blunt dissection are intraoperative hallmarks

🎯

LRINEC score uses CRP, WBC, haemoglobin, sodium, creatinine, and glucose. Score ≥6 = high risk; score ≥8 = very high risk, surgical exploration strongly indicated. A LOW score does NOT exclude necrotising fasciitis - clinical judgement always takes precedence.

Management

Three pillars proceed in parallel - not sequentially: resuscitation, broad-spectrum antibiotics, and emergency surgical debridement. Requires immediate MDT: colorectal/urology surgery, plastic surgery, ITU, microbiology, anaesthetics.

Step 1 · Resuscitation

1. 1IV fluid resuscitation
2. 2Oxygen, catheter, continuous monitoring
3. 3Correct coagulopathy, hyperglycaemia

↓

Step 2 · Empirical antibiotics (immediate)

1. 1Piperacillin-tazobactam + metronidazole + clindamycin - broad-spectrum cover for polymicrobial infection including anaerobes
2. 2Rationalise based on operative tissue MC&S results

↓

Step 3 · Emergency surgical debridement

1. 1Wide excision of all necrotic tissue - the definitive treatment
2. 2Relook surgery at 24-48 hours; repeat debridements until clean margins achieved
3. 3Vacuum-assisted closure (VAC) therapy between debridements to promote granulation

↓

Step 4 · Postoperative care and reconstruction

1. 1HDU/ITU for organ support
2. 2Hyperbaric oxygen - adjunct in specialist centres (inhibits anaerobes, promotes angiogenesis); limited mortality benefit evidence
3. 3Reconstructive surgery (skin grafting, flap repair) once wound clean and patient stable
4. 4Some patients require permanent colostomy

Complications

•Septic shock and multiorgan failure - leading cause of death

•Acute kidney injury - sepsis, hypotension, nephrotoxic antibiotics

•Extensive tissue loss requiring multiple debridements and prolonged reconstruction

•Erectile dysfunction and urethral stricture

•Psychological morbidity - body image disturbance, PTSD, depression

Prognosis

•Mortality 20-40% in modern series

•Fournier's Gangrene Severity Index (FGSI) - score >9 associated with mortality >75%

•Poor outcome predictors: older age, diabetes, extensive disease, delay to surgery, renal failure, septic shock on admission

•Time to first debridement is the key modifiable factor most strongly associated with survival

Key facts

•Male:female ratio ~10:1; peak incidence fifth/sixth decade

•Always polymicrobial - synergistic aerobes and anaerobes (E. coli, Klebsiella, Bacteroides, Streptococcus, Staphylococcus, Clostridium)

•Aerobes consume O2 → anaerobic environment → obliterative endarteritis → fascial ischaemia and necrosis → rapid spread along fascial planes

•Gas-producing organisms cause subcutaneous crepitus - pathognomonic sign