Prognostic Determinants and Scoring Systems in Fournier’s Gangrene: A Narrative Review

Background: Fournier’s gangrene (FG) is a necrotizing soft-tissue infection with substantial mortality. Objective: To critically compare prognostic determinants and scoring systems according to intended purpose, measurement timing, validation, and clinical applicability. Methods: This narrative review used searches of PubMed/MEDLINE, Web of Science, Scopus, and Google Scholar, with the final database search on 27 July 2026. Four authors independently selected publications and extracted data; two authors adjudicated disagreements. The documented selection retained 94 publications. Diagnostic accuracy, mortality association, and prognostic-model performance were considered separately. Results: Mortality was 19.8% in a 6152-case literature synthesis and 16.1% in a Spanish national cohort. A 40-study meta-analysis reported pooled areas under the receiver operating characteristic curve (AUCs) of 0.90 for the Fournier’s Gangrene Severity Index (FGSI), 0.94 for its Uludag modification (UFGSI), and 0.84 for its simplified form (SFGSI), derived from different subsets of 9, 6, and 3 studies, respectively. These estimates do not establish comparative superiority. SFGSI requires fewer laboratory variables; FGSI includes broader physiology; UFGSI additionally incorporates age and anatomical extent. The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) primarily supports diagnosis of necrotizing fasciitis. Neutrophil-to-lymphocyte ratio (NLR) thresholds show mortality associations but lack established external validation. General organ-dysfunction and comorbidity instruments address different domains. The Fournier’s Gangrene Mortality Index (FGMI) has limited external validation, whereas its platelet- and arterial-carbon-dioxide-augmented model (FGMI-2P) remains in model development. Conclusions: Instrument choice should reflect the clinical question, available data, and stage of care. The proposed framework has not been shown to improve decisions or outcomes beyond clinical assessment. Prognostic calculation must not delay resuscitation, antimicrobial treatment, or surgical source control.