Necrotizing Fasciitis / Fournier's Gangrene
Fournier's gangrene (FG) is necrotizing soft tissue infection (NSTI) of the perineal, genital or perianal region and is a surgical emergency. Prompt recognition, resuscitation, broad-spectrum antibiotics and urgent, often repeated debridement are central to treatment.[1][9] Infection is often polymicrobial but may be monomicrobial. Skin preservation is appropriate only when it preserves viable tissue without compromising source control.
Epidemiology
- A US National Inpatient Sample analysis for 2016–2020 identified 9,326 unweighted admissions: 2,875 women (31%) and 6,451 men (69%). In-hospital mortality was 7.1% versus 5.7%, respectively. Median annual incidence estimates were 1.7 per 100,000 women and 4.0 per 100,000 men.[3]
- Mortality is higher in many referral cohorts; case mix, shock, comorbidity and delayed source control affect outcomes. Population averages do not predict an individual patient's prognosis.[2]
- An older population study of 1,641 men at 593 hospitals found lower adjusted mortality at hospitals treating more FG cases; this observational association does not establish a causal volume threshold.[8]
Pathophysiology
FG originates from synergistic polymicrobial infection exploiting fascial planes with devastating speed. Common source sites include:
- Anorectal: anorectal abscess, anal fistula, rectal perforation
- Urogenital: urethral stricture, periurethral abscess, catheter trauma, urinary extravasation
- Cutaneous: trauma, pressure ulcer, surgical wound
The hallmark is obliterative endarteritis of subcutaneous vessels causing ischemic fascial necrosis with gas production, spreading rapidly along Colles', Scarpa's, and Dartos fascial planes. A critical insight with implications for surgical technique: the rich and redundant vasculature of the skin means cutaneous manifestations may appear much later than deep tissue necrosis — intact overlying skin may overlie extensively necrotic subcutaneous tissue, yet remain histologically viable and salvageable.[2][4] This underpins the modern skin-sparing surgical approach.
Infection can spread along Dartos fascia. The testes are commonly spared because their arterial supply arises separately through the spermatic cords, rather than from the scrotal skin circulation.
Microbiology
FG is polymicrobial in ~58% of cases; monomicrobial infection is documented in ~30%.[2] Mixed aerobic-anaerobic synergism is the rule, but the strict framing of FG as "invariably polymicrobial" is an overstatement.
| Category | Common Organisms |
|---|---|
| Aerobic gram-positive | Staphylococcus aureus (including MRSA), Streptococcus spp. (Group A), Enterococcus faecium |
| Aerobic gram-negative | Escherichia coli (most frequent overall), Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus spp. |
| Anaerobic | Bacteroides fragilis, Fusobacterium spp., Clostridium spp., Peptostreptococcus spp. |
Higher Mortality Organisms.
MRSA and Acinetobacter are independently associated with higher mortality in FG. Culture results should prompt early de-escalation or targeted therapy as sensitivities return.[2]
Risk Factors
| Category | Risk Factors |
|---|---|
| Metabolic | Diabetes mellitus (most common — 40–70% of cases), obesity, malnutrition |
| Immunosuppression | HIV/AIDS, malignancy, corticosteroids, chemotherapy, organ transplant |
| Vascular | Peripheral vascular disease, chronic venous insufficiency |
| Local predisposing | Urethral stricture, perianal abscess, anorectal fistula, urinary instrumentation, trauma |
| Behavioral | Alcohol use disorder, intravenous drug use |
| Novel | Sarcopenia (independent risk factor for mortality)[2] |
| Medication | SGLT-2 inhibitors carry a regulatory warning for rare FG. A nonsignificant association in studies with few events does not eliminate the warning; suspected FG requires prompt treatment and discontinuation of the SGLT-2 inhibitor[2][5] |
Clinical Presentation and Diagnosis
Clinical Features
Early FG may be mistaken for cellulitis or scrotal abscess. Progression to frank necrosis can occur within hours.
Early: Perineal/scrotal erythema, pain, and edema out of proportion to visible skin changes; induration; fever, tachycardia
Late: Gray/bronze/violaceous skin discoloration with blistering; crepitus on palpation; foul-smelling discharge; cutaneous gangrene; septic shock
Operate on Clinical Diagnosis — Do Not Wait for Imaging.
The clinical diagnosis of FG is made at the bedside. Do not delay operative debridement in a patient with systemic sepsis and perineal crepitus or necrosis. CT is valuable for delineating extent and identifying source in equivocal cases but must never delay surgery in an obvious presentation.[1]
Imaging
| Modality | Performance | Notes |
|---|---|---|
| CT abdomen/pelvis with IV contrast | In a broader adult NSTI meta-analysis: sensitivity 88.5%, specificity 93.3%[12] | Assesses extent/source; gas supports concern but is neither required nor independently diagnostic |
| Point-of-care ultrasound | Real-time; operator-dependent | May identify superficial collections; limited deep fascial assessment |
| MRI | Superior soft tissue characterization | Slow acquisition limits emergency use; impractical in unstable patients |
| Plain radiograph | Low sensitivity | May detect gross subcutaneous gas; insufficient for planning |
Severity Scoring
Fournier's Gangrene Severity Index (FGSI)
Developed by Laor et al. (1995);[6] uses 9 physiological parameters scored 0–4 based on deviation from normal. The table shows selected extreme abnormalities only and is not a complete scoring calculator:
| Variable | Abnormal Deviation | Max Points |
|---|---|---|
| Temperature (°C) | ≥41 or <30 | 4 |
| Heart rate (bpm) | ≥180 or <40 | 4 |
| Respiratory rate | ≥50 or <6 | 4 |
| Serum sodium (mEq/L) | ≥160 or <111 | 4 |
| Serum creatinine (mg/dL) | >3.5 | 4 |
| Serum potassium (mEq/L) | ≥7.0 or <2.5 | 4 |
| Hematocrit (%) | ≥60 or <20 | 4 |
| WBC (×1,000/mm³) | ≥40 or <1 | 4 |
| Serum bicarbonate (mEq/L) | <15 | 4 |
In the original 30-patient series, FGSI ≤9 corresponded to 78% survival and >9 to 75% mortality. These derivation-cohort estimates are not fixed bedside probabilities.
Other prognostic scores
The Uludag FGSI adds age and disease extent. The simplified FGSI uses potassium, creatinine and hematocrit. Performance varies across derivation and validation cohorts; reported AUCs or mortality cutoffs should not be presented as universal probabilities.[2]
CRP Ratio as Mortality Predictor
A retrospective 52-patient study defined the ratio as preoperative CRP divided by CRP 48 hours after surgery. A ratio ≤1.78 was associated with mortality (sensitivity 86%, specificity 82% within this cohort). This is an exploratory prognostic finding, not a validated trigger for reoperation; source-control decisions depend on the whole clinical course and repeated wound assessment.[13]
LRINEC Score
The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) incorporates WBC, CRP, hemoglobin, sodium, creatinine, and glucose.[7] In a meta-analysis of adults evaluated for NSTI, score ≥6 had sensitivity 68.2% and specificity 84.8%.[12] A negative LRINEC does not exclude NSTI.
Scores Are Prognostic — Not Decision Tools. All scoring systems provide prognostic information and can guide ICU communication and family counseling. They must never delay or defer operative intervention in a clinically apparent or deteriorating patient.
Surgical Management
Timing
Arrange urgent surgical debridement. Delayed source control is associated with worse outcomes. Begin resuscitation, antibiotics and anesthetic/operative preparation in parallel; avoid unnecessary delays while addressing immediate physiologic threats.[3][9]
Skin-Sparing Debridement — Modern Paradigm
Historical radical debridement excised all tissue through to healthy, non-cellulitic margins, often sacrificing viable skin and creating large defects requiring complex reconstruction. Contemporary evidence supports a skin-sparing approach: because the rich cutaneous vasculature may preserve skin viability even over necrotic subcutaneous tissue, the emphasis is on excising only dead or severely compromised tissue.[2][4]
Tom et al. studied 487 patients with NSTI at one institution, comparing an earlier traditional-debridement cohort (230) with a later skin-sparing cohort (257). Mortality did not differ significantly. Median proportion of wound area closed primarily was 0% versus 50%, and skin-grafted area 90% versus 20%. These are wound-area outcomes, not percentages of patients achieving closure; the temporal, nonrandomized comparison cannot prove equivalent safety or a benefit specific to FG.[4]
Operative Technique
Positioning: Lithotomy for wide perineal, scrotal, and genital exposure
Incision strategy: Tailor exposure to the involved fascial compartments. Remove necrotic tissue fully and reassess doubtful tissue; preserving viable skin must not limit adequate exposure or source control.
Blunt dissection distinguishes healthy from necrotic planes. Healthy tissue bleeds briskly; necrotic tissue does not. The finger test — finger dissection proceeds through normally adherent fascial planes without resistance — supports the diagnosis of NSTI in the appropriate clinical context.
Wound left open after debridement — never close at initial operation.
Extent of debridement:
- All visibly necrotic skin, subcutaneous tissue, and fascia
- Extend along fascial planes to bleeding margins
- Scrotum: Orchiectomy rarely required — testicular blood supply is preserved through spermatic cord
- Penis: Debride necrotic Dartos and Buck's fascia; penectomy very rarely required
- Perineum/perirectal: May extend to ischiorectal fossa; consider loop colostomy when anorectal source is identified, perirectal involvement is extensive, or stool contamination threatens wound healing
- Urinary diversion: SPT recommended when extensive perineal involvement is present or urethral injury has occurred
Re-Look Operations Are Mandatory.
IDSA advises return to the OR 24–36 hours after initial debridement and daily thereafter as needed until no further debridement is required.[9] Areas appearing viable at initial debridement may become ischemic within 24–72 hours post-mobilization. Inadequate single-operation approaches are associated with increased mortality — re-look is not a sign of incomplete initial surgery, it reflects the evolving biology of the disease.
Antimicrobial Therapy
Broad-spectrum empiric antibiotics must be initiated immediately upon diagnosis:[9]
Standard polymicrobial coverage options (IDSA-based):
| Regimen | Components |
|---|---|
| Option 1 | Linezolid + Piperacillin-tazobactam |
| Option 2 | Vancomycin + Clindamycin + Piperacillin-tazobactam |
| Alternative broad regimens | Linezolid + Meropenem; or Linezolid + Cefepime/Ceftriaxone + Metronidazole |
| Critically ill (broad) | Vancomycin or linezolid plus a carbapenem (meropenem or imipenem-cilastatin); carbapenem alone does not cover MRSA |
Select agents and doses for renal function, local resistance and allergy phenotype; the alternatives above are not universal regimens for every penicillin allergy. For documented group A streptococcal necrotizing fasciitis, IDSA recommends penicillin plus clindamycin.[9]
De-escalate antibiotics based on intraoperative wound cultures (obtain at initial debridement). IDSA recommends continuing until further debridement is unnecessary, clinical improvement is evident, and fever has been absent for 48–72 hours; bacteremia or another infection may require a longer course. A fixed additional 7–14 days after source control is not required for every case.[9]
Adjunct and Investigational Therapies
| Therapy | Evidence | Recommendation |
|---|---|---|
| Hyperbaric oxygen (HBO) | Controversial; some studies suggest mortality benefit, others no benefit; RCT data lacking | May be considered as adjunct at centers with HBO capability; never delays surgery |
| IVIG | Benefit in streptococcal toxic shock remains uncertain; routine benefit in FG is not established[9] | Not recommended routinely |
| Reltecimod | 2020 trial showed promising trends but no significant benefit in modified intent-to-treat analysis; FDA unapproved[2] | Investigational; not standard of care |
Wound Management
Choose wound care after adequate debridement according to tissue viability, anatomy and contamination:
- Saline or appropriately diluted antiseptic dressings may be used; antiseptics can be cytotoxic at higher concentrations. Laboratory biofilm killing should not be described as clinical wound sterilization.
- Negative-pressure wound therapy can assist exudate control and wound preparation. It does not replace repeated source control. The 35-patient Czymek comparison had selection/survivor bias and does not establish a mortality benefit.[10]
- Temporary testicular thigh pouches are an option in selected extensive scrotal defects, with later functional and reconstructive counseling.
Reconstruction
Reconstruction is deferred until infection has resolved, wound is clean with healthy granulation, and systemic illness has cleared ; timing depends on the wound and patient rather than a fixed interval.[1]
A 2024 review included 38 studies, mainly small observational series. Its abstract and results use inconsistent reconstruction denominators (576 versus 593), so precise pooled technique percentages should be interpreted cautiously. Direct closure, secondary healing, grafts and local flaps were commonly reported; no included study reported a free flap. This is not evidence that free flaps have never been used for FG.[11]
| Wound Extent | Preferred Option |
|---|---|
| Small defects | Secondary intention or delayed primary closure (modern preference) |
| Moderate scrotal defects | Split-thickness skin graft (STSG) — preferred over FTSG for take rate |
| Large scrotal / perineal defects | STSG; gracilis myocutaneous flap for deep perineal floor defects |
| Complex loco-regional needs | Anterolateral thigh, superomedial thigh, groin, SCIP, or Limberg transposition flap |
| Extensive scrotal loss with exteriorized testicles | Thigh pouch; eventual flap reconstruction when conditions allow |
| Penile shaft skin loss | STSG over corporal bodies |
Delayed primary closure is useful when viable tissue can be approximated without tension after infection control. The Tom study supports feasibility of greater wound-area closure in selected NSTI patients, not a universal 50% patient closure rate.[4]
Tissue expanders are contraindicated in the setting of complete scrotal loss. Testicular thigh pouches, while simple to perform, carry concerns about temperature regulation and testicular function — patient preference for reconstruction approach should be elicited.
Colostomy reversal (when performed) is typically planned at 3–6 months after the index operation once complete recovery is confirmed.
Patient-reported outcomes: comparative functional, sexual and body-image outcomes remain limited in the reconstructive literature. Discuss these goals explicitly rather than treating wound closure alone as recovery.[11]
References
1. American College of Surgeons Trauma Quality Programs. ACS TQP Best Practices Guidelines: Management of Genitourinary Injuries. Chicago, IL; August 2025. Full guideline
2. Kopechek KJ, Patel HV, Koch GE. Modern Management of Fournier's Gangrene. Curr Urol Rep. 2025;26(1):47. PMID 40455358 doi:10.1007/s11934-025-01275-3
3. Abbasi B, Hacker E, Ghaffar U, et al. Higher Morbidity and Mortality in Females With Fournier Gangrene Compared With Males: Insights From National Inpatient Sample Data. J Urol. 2025;213(1):99–109. doi:10.1097/JU.0000000000004264.
4. Tom LK, Maine RG, Wang CS, Parent BA, Bulger EM, Keys KA. Comparison of Traditional and Skin-Sparing Approaches for Surgical Treatment of Necrotizing Soft-Tissue Infections. Surg Infect. 2020. doi:10.1089/sur.2019.263.
5. US Food and Drug Administration. FDA warns about rare occurrences of a serious infection of the genital area with SGLT2 inhibitors for diabetes. FDA Drug Safety Communication. August 29, 2018. See also Health Sciences Authority safety communication.
6. Laor E, Palmer LS, Tolia BM, Reid RE, Winter HI. Outcome prediction in patients with Fournier's gangrene. J Urol. 1995;154(1):89–92. PMID 7776464
7. Wong CH, Khin LW, Heng KS, Tan KC, Low CO. The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: A tool for distinguishing necrotizing fasciitis from other soft tissue infections. Crit Care Med. 2004;32(7):1535–1541. PMID 15241098
8. Sorensen MD, Krieger JN, Rivara FP, et al. Fournier's Gangrene: Management and mortality predictors in a population based study. J Urol. 2009;182(6):2742–2747. PMID 19837424
9. Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections: 2014 update by the IDSA. Clin Infect Dis. 2014;59(2):e10–52. PMID 24973422
10. Czymek R, Schmidt A, Eckmann C, et al. Fournier's gangrene: Vacuum-assisted closure versus conventional dressings. Am J Surg. 2009;197(2):168–176. PMID 19185110
11. Susini P, Marcaccini G, Efica J, et al. Fournier's Gangrene Surgical Reconstruction: A Systematic Review. J Clin Med. 2024;13(14):4085. doi:10.3390/jcm13144085.
12. Fernando SM, Tran A, Cheng W, et al. Necrotizing Soft Tissue Infection: Diagnostic Accuracy of Physical Examination, Imaging, and LRINEC Score: A Systematic Review and Meta-Analysis. Ann Surg. 2019;269(1):58–65. doi:10.1097/SLA.0000000000002774.
13. Eray IC, Dalci K, Gumus S, et al. The role of C-reactive protein ratio in predicting mortality in patients with Fournier gangrene. Ann Coloproctol. 2023;39(3):223–230. doi:10.3393/ac.2021.00843.0120.