Is fistulotomy with immediate sphincter reconstruction (FISR) a sphincter preserving procedure for high anal fistula? A systematic review and meta-analysis.

AIM: This systematic review aimed to assess the outcomes of fistulotomy or fistulectomy and immediate sphincter repair (FISR) in relation to healing, incontinence and sphincter dehiscence both overall and in patients with high anal fistulae. METHODS: Medline, Embase and The Cochrane library were searched for studies of patients undergoing FISR for anal fistula. Data regarding healing, continence and sphincter dehiscence were extracted overall and for high anal fistulae. The DerSimonian-Laird random-effects method was used for pooled analysis, heterogeneity between studies was assessed based on the significance of between-study heterogeneity, and on the size of the I2  value. Risk of bias was assessed using the Cochrane risk of bias tool and the Newcastle-Ottawa scale. RESULTS: We identified 21 studies evaluating 1700 patients. Pooled analysis of healing reached 93% (95% CI: 91%-95%, I2  = 51% p-value for heterogeneity = 0.004), with continence disturbance and worsening continence reaching 11% (95% CI: 6%-18%, I2  = 87% p < 0.001) and 8% (95% CI: 4%-13%, I2  = 74% p < 0.001), respectively. Subgroup analysis according to fistula height could only be conducted on limited data. Pooled healing in high anal fistulae was 89% (95% CI: 84%-94%, I2  = 76% p < 0.001), 16% suffered disturbance of continence (95% CI: 7%-27%, I2  = 89% p < 0.001), 8% worsening continence from baseline (95% CI: 2%-16%, I2  = 80% p < 0.001) and 2% suffered sphincter dehiscence (95% CI: 0%-10%, I2  = 89% p < 0.001). CONCLUSION: The evidence suggests FISR is a safe, effective procedure. However, data are limited by inconsistencies in reporting of continence and definition of fistula height, particularly high anal fistulae. Significant heterogeneity means that outcomes in high fistulae remain uncertain.