QS112 - Patterns and Management of Deep Fascial Spread in Perianal Necrotizing Fasciitis: A Single-Center Experience

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Purpose/Background: Perianal necrotizing fasciitis (PNF) is a severe infectious disease caused by multiple bacterial pathogens, characterized by rapid necrosis of the skin and soft tissue in the perianal and perineal regions. While the incidence of PNF is low, its mortality rate ranges from 9% to 25%, due to challenges in early diagnosis and rapid clinical progression. Understanding the patterns of deep fascial spread in PNF is crucial for improving clinical management outcomes.

Methods/Interventions: We conducted a retrospective analysis of 110 patients diagnosed with PNF at a single center over the past six years. All cases underwent surgical debridement, and fascial spread was monitored through imaging and clinical progression. The study focused on distinguishing between superficial (An infection that spreads along the subcutaneous adipose tissue without invading the potential intermuscular spaces) and deep fascial (An infection that spreads along the extraperitoneal spaces (pelvic and abdominal) or extends through intermuscular spaces) infections and tracing their respective pathways, particularly in the region above and below the deep fascia of the levator ani muscle.

Results/Outcomes: Among the 110 patients (101 males, 8 females), 95 presented with superficial fascial infections and 15 with deep fascial infections. There were three fatalities, all associated with deep fascial spread. We observed that deep fascial infections followed specific paths (MRI of representative cases is shown in Figure 1), including:①Deep fascial spread above the levator ani—primarily through two pathways: ascending via the levator ani tendon arch and ascending intermuscularly;②Intermuscular spread pathway—typically did not involve the mesorectum but could extend between the mesorectal fascia and pelvic wall fascia;③Deep fascial spread below the levator ani—primarily extended through the deep surface of the gluteus maximus, potentially spreading intermuscularly into the lower extremity.For surgical approaches, we developed and refined several techniques:①For extraperitoneal infections above the pubic symphysis, we recommend a pararectal incision above the symphysis, with communication to the corresponding lower ischiorectal fossa incision to facilitate drainage;②For ascending intermuscular deep fascial infections, we suggest intermuscular drainage with catheter irrigation, while infections spreading upward via the levator ani tendon arch are better managed through extramuscular catheterization.

Conclusion/Discussion: Deep fascial infections in PNF are associated with a higher mortality rate due to rapid spread and sepsis-related complications. Early and aggressive surgical intervention, combined with high-dose antibiotic therapy, is crucial. Based on our single-center data, we differentiated the infection of PNF into superficial and deep fascial areas, and refined the diagnostic and treatment protocol for PNF (Figure 2), emphasizing the importance of deep fascial dissemination. The fascial spread patterns identified in this study provide essential insights for surgical planning, underscoring the importance of early detection and comprehensive drainage of affected areas to improve patient outcomes.