Fournier’s Gangrene

Introduction

Fournier’s gangrene (FG) is a form of necrotising fasciitis that affects the soft tissues of the perineal, genital or perianal regions.

FG is a rare but rapidly progressive disease with a high mortality rate. It is a surgical emergency which requires early recognition and management.

Aetiology

Fournier’s gangrene results from a monomicrobial or polymicrobial (i.e. a mix of aerobic and anaerobic bacteria) infection of the fascia and subcutaneous soft tissue of the perineal, genital or perianal regions. 

This may be idiopathic. However, it is typically secondary to the spread of organisms from another focus of infection:¹ 

• Colorectal: trauma, abscesses, appendicitis, diverticulitis, colon cancer
• Genitourinary: trauma, epididymitis, orchitis, urethral catheterisation, urethral stricture, urethral stone, urological surgery 
• Cutaneous: perineal trauma, perineal/pelvic surgery, superficial scrotal infection

The most common organisms that cause FG are skin commensals. These include Staphylococci, Streptococci, Bacteroides, Coliforms, Clostridia, Klebsiella and Corynebacteria.¹

Pathophysiology

Enzymes produced by the bacteria cause coagulation and thrombosis of local blood vessels, reducing local blood supply. This results in cutaneous and subcutaneous vascular necrosis, leading to localised ischaemia and bacterial proliferation.³

The enzymes also lead to the digestion of fascial barriers, allowing rapid extension of the infection. 

Anatomy

FG mostly affects the skin and subcutaneous tissue. Deep fascial layers and muscles are not usually involved. The testes and spermatic cords are generally unaffected as they have an independent blood supply.

Risk factors

Risk factors for the development of FG include:

• Trauma and skin injury to the perineal, genital or perianal regions
• Alcoholism
• Impaired immunity (e.g. diabetes mellitus, steroid use, malignancy, HIV, malnutrition)
• Male sex: FG occurs in a M:F ratio of 10:1

Clinical features

Early presentation may be non-specific and subtle until the infection becomes severe with clinical deterioration.

History

Typical symptoms of Fournier’s gangrene may include:

• Pain which is often severe and out of proportion to clinical lesions 
• Itching
• Erythema and skin discoloration   
• Systemic symptoms: fever, tachycardia, hypotension, nausea & vomiting, malaise, confusion 

Clinical examination

Typical findings on examination of the perineal, genital and perianal regions include: 

• Tenderness
• Oedema
• Skin changes often with poorly defined margins (e.g. erythema, induration, red and purple patches, tense skin)
• Skin necrosis and gangrene: black, dry and hard skin
• Crepitus: a crackling sound on palpation
• Purulent discharge with the appearance of dirty dishwasher fluid 
• Bullae and ulcers 

In males, the scrotum and penis are the most commonly involved areas, whilst in females, the labia is most affected.

Differential diagnoses

Differential diagnoses to consider include other causes of skin changes and pain in the affected regions. The key feature differentiating FG from these conditions is pain disproportionate to the clinical findings and severe systemic signs.

Cellulitis/erysipelas/impetigo

These soft tissue infections are milder than FG and tend to present with tenderness and well-demarcated areas of erythema and systemic signs of infection such as fever and lethargy.

FG is a more severe disease in which the skin changes include erythema; however, this is poorly demarcated in FG and may also include blisters and bullae in the late stages. In FG, patients tend to be more systemically unwell and may have multiorgan failure.

Epididymo-orchitis

This refers to inflammation of the epididymis and/or testes with or without infection.

Like FG, it may also present with scrotal pain and tenderness. However, it is a more gradual presentation and on examination, this may be relieved by manual elevation of the testes (Phren’s sign). In younger patients, it is associated with sexually transmitted infections.

Testicular torsion

Testicular torsion occurs due to the twisting of the spermatic cord, resulting in a sudden loss of testicular blood supply.

Like FG, this may present with sudden scrotal pain. However, unlike in FG, the testes have an abnormal lie and a negative cremasteric reflex.

Renal colic

Renal colic refers to pain felt due to the passage of ureteric stones. It often presents with colicky loin to groin pain and systemic symptoms if there is an element of infection. Skin changes are not usually present with renal colic.

Investigations 

The following may be used to support the diagnosis of FD.⁴ 

Laboratory investigations

Relevant laboratory investigations include:

• Full blood count (FBC): white cell count (WCC) will typically be elevated
• CRP: typically elevated
• Urea and electrolytes (U&Es): may show any concurrent renal failure and electrolyte abnormalities 
• Glucose: may be elevated secondary to diabetes or infective process
• ABG: to assess oxygenation status, acid/base status and lactate. If an acid-base imbalance is present, it is usually metabolic acidosis, and lactate may be high. 
• Blood cultures: to identify causative organisms 
• Coagulation: as part of pre-operative workup, may be deranged secondary to DIC
• Group and save: as part of a pre-operative workup 

Imaging

Relevant imaging investigations include:

• Ultrasound: a quick examination that may help visualise subcutaneous gas or emphysema in underlying soft tissue, especially before it becomes clinically visible. 
• X-ray: may show soft tissue gas.
• CT: the most sensitive and specific form of imaging in the diagnosis of Fournier’s gangrene. May show fat stranding, subcutaneous emphysema, abscess and fluid collections. 

Microbiology

Relevant microbiology investigations include:

• Urine cultures: to identify concurrent UTI and causative organisms which may be the primary source of infection 
• Wound/abscess/tissue cultures: to identify causative organisms

Diagnosis

The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score can be used to identify early necrotising fasciitis, including FG. A score is generated using the CRP, WCC, haemoglobin, sodium, creatinine and glucose.⁵

However, the diagnosis of FG is primarily clinical. In cases where the diagnosis is clear, the patient is unstable or septic, treatment should be commenced without waiting for confirmatory investigations.

Microbiological classification

The organisms which cause FG may be classified using the microbiological classification of necrotising fasciitis, which is divided into four types:²

• Type 1: polymicrobial process with bowel-derived flora. Organisms are usually a mix of anaerobes and aerobes. This is the most common and makes up 70-80% of cases. The site of infection is most frequently the trunk and perineum.
• Type 2: monomicrobial, with the initial infection arising from the skin or throat. Organisms are usually group A β-haemolytic streptococcus (GAS), occasionally S. aureus. The site of infection is most frequently the limbs.
• Type 3: involves gram-negative, often marine-related organisms such as Vibrio spp. The site of infection is most frequently the limbs, trunk and perineum.
• Type 4: a fungal process and is usually trauma-related. Organisms include Candida (in immunocompromised patients) and zygomycetes (in immunocompetent patients).

Management

The mainstay treatment is early surgical debridement with adequate resuscitation and antibiotics, followed by reconstructive surgery.⁴

Medical management

Resuscitation

Unstable patients should primarily undergo urgent resuscitation using the ABCDE approach, with the use of fluids and inotropes as required. 

Antibiotics

Empiric broad-spectrum intravenous antibiotics with good gram-positive, gram-negative and anaerobic cover should be administered as soon as FG is suspected. The initial antibiotic choice should follow local guidelines.

Antibiotics should later be tailored according to the culture results of any tissue or fluid samples sent.

Treatment of predisposing conditions and complications

This includes the medical management of underlying conditions which may have predisposed to developing FG (e.g. diabetes and malnutrition). 

Some complications that arise from FG also require medical management, such as acute kidney injury (AKI) and arrhythmias. 

Surgical management

Debridement

Definitive management involves early surgical exploration and debridement of necrotic and gangrenous tissue. This should be prompt and without delay to reduce the risk of severe illness and complications.

It may need to occur in stages, requiring multiple procedures for relooks and debridement for complete removal of necrotic tissue until a healthy wound base is achieved.

Reconstructive surgery

FG may result in significant subcutaneous tissue and skin loss and defects, which require reconstructive surgery by plastic surgeons for adequate wound coverage and functional restoration.

Possible reconstructive options include:^6,7

• Secondary healing or delayed primary closure: used for small defects
• Split thickness skin graft (STSG): this is used in cases with a large area of skin loss
• Full-thickness skin graft: used for urethroplasty in urethral structures 
• Scrotal advancement flap: uses local tissue, used for small scrotal defects
• Fasciocutaneous flap (e.g. pudendal thigh flap): composed of skin, subcutaneous tissue and fascia and used for larger scrotal defects 
• Myocutaneous flap (e.g. gracilis flap): composed of skin, subcutaneous tissue, fascia and muscle and therefore used in cases with a deep soft tissue defect with dead space

Other treatments

Other treatments may include hyperbaric oxygen therapy and vacuum-assisted closure (VAC). They are used in more severe and complicated cases as a part of multidisciplinary management:

• Hyperbaric oxygen therapy: results in increased tissue oxygenation and enhanced wound healing.⁸ 
• Vacuum-assisted closure (VAC): a dressing system which exposes the wound to subatmospheric pressure to promote healing.⁹ VAC promotes wound healing and decreases cavitation before eventual reconstruction.

Complications 

Systemic complications

Fournier’s gangrene is an infectious process which causes a systemic response and complications:⁴

• Acute kidney injury
• Acute respiratory distress syndrome (ARDS)
• Cardiac arrhythmias: especially if electrolyte abnormalities are present
• Sepsis
• Multiorgan failure 
• Bacteraemia: this can cause acute thromboembolic events which may lead to cerebrovascular accidents and arterial occlusions in the extremities of the limbs requiring amputations 

Local complications

Patients with significant involvement of the perineum may develop:⁴

• Faecal incontinence: if there is involvement of the anal sphincter requiring debridement. This may require a colostomy to divert the faeces away from the wound
• Urinary tract infections: more common if the penis is involved 
• Urinary retention: secondary to periurethral swelling 
• Sexual dysfunction: which may be secondary to psychological effects and physical changes to the penis

Psychological complications

Fournier’s gangrene has a significant disease burden, often with multiple procedures being required and resultant physical changes, which may lead to a decreased quality of life and depression.¹⁰

Key points

• Fournier’s gangrene (FG) is a form of necrotising fasciitis that affects the soft tissues of the perineal, genital or perianal regions.
• Risk factors include impaired immunity and local skin trauma.
• The presentation may be nonspecific in the early stages, however early recognition and management is essential.
• Symptoms may include pain, often out of proportion to clinical lesions and skin changes, including erythema and necrosis.
• Investigations may include blood tests, microbiology investigations and imaging. However, FG is a clinical diagnosis and investigations should not delay management.
• Definitive management is with antibiotics and surgical debridement.
• Subsequent reconstructive surgery may be required for adequate wound closure and functional restoration.

Reviewer

Mr. Kurt Lee Chircop M.D. (Melit.) MRCSI MSc

Plastic and Reconstructive Surgery Registrar

Editor

Dr Jess Speller

References

1. Eke N. Fournier’s gangrene: A review of 1726 cases. 2002. British Journal of Surgery. Available from: [LINK]
2. Davoudian P, Flint NJ. Necrotizing fasciitis. 2012. Continuing Education in Anaesthesia Critical Care & Pain. Available from: [LINK]
3. Mallikarjuna MN, Vijayakumar A, Patil VS, Shivswamy BS. Fournier’s gangrene: Current practices. 2012. ISRN Surgery. Available from: [LINK]
4. Leslie SW, Rad J, Foreman J. Fournier Gangrene. 2023.  StatPearls. Available from: [LINK]
5. Wong C-H, Khin L-W, Heng K-S, Tan K-C, Low C-O. The LRINEC (laboratory risk indicator for necrotizing fasciitis) score: A tool for distinguishing necrotizing fasciitis from other soft tissue infections. 2004. Critical Care Medicine. Available from: [LINK]
6. Chen S-Y, Fu J-P, Wang C-H, Lee T-P, Chen S-G. Fournier gangrene. 2010. Annals of Plastic Surgery. Available from: [LINK]
7. Chen S-Y, Fu J-P, Chen T-M, Chen S-G. Reconstruction of Scrotal and perineal defects in Fournier’s gangrene. 2011. Journal of Plastic, Reconstructive & Aesthetic Surgery. Available from: [LINK]
8. Riseman JA, Zamboni WA, Curtis A, Graham DR, Konrad HR, Ross DS. Hyperbaric oxygen therapy for necrotizing fasciitis reduces mortality and the need for debridements. 1990. Surgery. Available from: [LINK]
9. Weinfeld AB, Kelley P, Yuksel E, Tiwari P, Hsu P, Choo J, et al. Circumferential negative-pressure dressing (VAC) to bolster skin grafts in the reconstruction of the penile shaft and scrotum. 2005. Annals of Plastic Surgery. Available from: [LINK]
10. Czymek R, Kujath P, Bruch H ‐P., Pfeiffer D, Nebrig M, Seehofer D, et al. Treatment, outcome and quality of life after fournier’s gangrene: A multicentre study. 2013. Colorectal Disease. Available from: [LINK]