Efficacy of Permacol injection for perianal fistulas in a tertiary referral population: poor outcome in patients with complex fistulas

Aim Injection of Permacol collagen paste can be used as a sphincter‐sparing treatment for perianal fistulas. In a tertiary referral population we aimed to evaluate the efficacy of Permacol injection and the clinical and fistula‐related factors associated with recurrence. Method This was a retrospective analysis of consecutive patients with perianal fistulas treated with Permacol injection at a specialist centre between June 2015 and April 2019. Endoanal ultrasonography was systematically reanalysed, blinded to treatment outcome. Rectovaginal, anovaginal and Crohn's disease fistulas were excluded. Healed fistulas were defined as absent anal symptoms and a closed external opening on physical examination at a minimum follow‐up of 6 months. Regression analyses were performed to identify factors associated with unhealed fistulas. Results A total of 90 patients (51 men; median age 45 years) were analysed. Seventy‐two (80.0%) patients had complex perianal fistulas (greater than one‐third sphincter involvement or multiple tracts). After a single Permacol injection, fistulas were healed in 20 (22.2%) patients at 3 months follow‐up and in 18 (20.0%) patients at a median follow‐up of 30 months (interquartile range 17–37). Eight (11.1%) patients with unhealed fistulas had significant improvement in their symptoms. Complex fistulas were significantly associated with unhealed status [OR 3.53 (95% CI 1.12–11.09); p = 0.031]. Twenty patients underwent subsequent Permacol injections, which were successful in six (30.0%) patients after one (n = 3) or two (n = 3) additional injections. Conclusion This largest study to date in patients with mainly complex perianal fistulas, demonstrated that the efficacy of a single Permacol injection was only 20%. Complex fistulas were associated with a poor outcome.