Introduction
Fournier’s gangrene is a form of necrotising fasciitis that affects the perineum. Whilst rare, it is a urological emergency with a mortality rate of 20-40%*.
Necrotising fasciitis is a group of rapidly spreading necrosis of subcutaneous tissue and fascia, the term also encompassing Fournier’s gangrene. Much of the principles for its management therefore hold true for Fournier’s.
Fournier’s Gangrene can be monomicrobial, but is more commonly a polymicrobial infection (usually mixed aerobic and anaerobic organisms). Causative organisms include Group A Streptococcus, Clostridium species (especially C.Perfringes), Pseudomonas Aeruginosa, and E.coli.
Infection in Fournier’s gangrene spreads by tracking along the superficial fascial planes of the perineum (Colles’ fascia), genitalia (Dartos fascia), and abdominal wall (Scarpa’s fascia). Often the testes and epididymis will be spared because they are deep to these fascial planes and receive a separate blood supply.
*The condition was first described by Jean Alfred Fournier, who described 5 cases involving previously healthy young men, all of which survived
Risk factors
Diabetes mellitus, excess alcohol intake, poor nutritional state, excess steroid use, haematological malignancies, and recent trauma or urological instrumentation to the region (allowing the protective outer layers of the perineum to be breached) are all known risk factors.
Clinical Features
Early stage of the condition may simply present with severe pain, out of proportion to clinical signs, or as pyrexia. Clinical features are often non-specific until significant deterioration, most commonly seen in those who are “not quite right” for a simple cellulitis.
As the condition progresses, there may be visible skin discolouration (ranging from dusky patches to black necrosis), palpable crepitus within the tissues, or discharging or haemorrhaging bullae. The features may be seen to rapidly spread from their initial site to surrounding tissues. Concerningly, these signs may not develop until well after the patient has significantly deteriorated.
If left untreated, patients will rapidly deteriorate and become significantly unwell, often developing septic shock and multi-organ failure.
Figure 1 – A case of Fournier’s gangrene following extensive debridement
Differential Diagnoses
As with any case of suspected necrotising fasciitis, the main differential in the early stage is a cellulitis. For potential Fournier’s gangrene cases, further differentials will include epididymo-orchitis, testicular torsion, incarcerated inguinal hernia, perianal abscess, pyoderma gangrenosum, or pressure ulcers.
Investigation
Diagnosis is largely clinical. Early sepsis management should be initiated, with active monitoring to assess for disease progression appropriate in uncertain cases. However, suspected cases should be taken to theatre early for immediate surgical exploration and debridement.
Ensure routine bloods (FBC, CRP, U&Es, LFTs, clotting, and lactate) and blood cultures should be taken. In the absence of any obvious risk factor, an HbA1C test can be considered be sent to assess for underlying diabetes mellitus.
CT imaging can show fascial swelling and soft tissue gas, however is less specific and should not delay surgical intervention.
Risk Scores for Necrotising Fasciitis
A diagnostic scoring system called the Laboratory Risk Indicator for Necrotising Fasciitis (LRINEC) can be used to aid in the diagnosis of necrotising fasciitis, including Fournier’s Gangrene.
Based on laboratory factors, a LRINEC score ≥6 is a reasonable score to consider the diagnosis based on lab results alone. Whilst the LRINEC can be a useful tool, it is not widely accepted in the everyday practise due to low sensitivity and should not delay treatment where there is reasonable clinical suspicion.
| 0 | +1 | +2 | +4 | |
| C-Reactive Protein (mg/L) | <150 | – | – | ≥150 |
| White Cell Count (x103/µL) | <15 | 15-25 | >25 | – |
| Haemoglobin (g/dL) | >13.5 | 11.0-13.5 | <11 | – |
| Sodium (mEq/L) | ≥135 | – | <135 | – |
| Creatinine (µmol/L) | ≤141 | – | >141 | – |
| Glucose (mmol/L) | ≤180 | >180 | – | – |
Table 1 – The Laboratory Risk Indicator for Necrotising Fasciitis
Management
The definitive management is urgent surgical debridement and this should not be delayed. Debridement can often be extensive, however ensuring adequate removal of all necrotic tissue is key; debrided tissue should be sent for both tissue histology and culture separately (MC&S) and any pus sent for fluid culture (MC&S) too
Prior to theatre, initial treatment should follow sepsis management protocols including intravenous fluids and broad spectrum empiric antibiotics (these can be tailored accordingly once culture sensitivities are available)
Patients will almost certainly require transfer to a high dependency setting post-operatively. Wounds are often left open and packed, as many require a relook procedure +/- further surgical debridement within 24-48 hours of their index procedure.
Secondary closure with skin grafts can be a long process, therefore early involvement of plastic surgeons is key. Post-operative outcomes vary, depending on disease extent and tissue involvement.
*The surgical debridement may also encompass partial or total orchiectomy, depending of the size of expansion of the process, with the wound usually left open.
Key Points
- Fournier’s gangrene is a form of necrotising fasciitis that affects the perineum
- Risk factors include diabetes mellitus, excess alcohol, or poor nutritional state
- Clinical features are often non-specific in the conditions early stages, before rapid deterioration occurs
- Definitive management is urgent surgical debridement with broad-spectrum antibiotic cover
