Dogma versus Evidence in Benign Proctology Anal Fistula, From Radical Fistulotomy to Sphincter-Sparing Repair

For more than a century, laying open the fistula tract was held to be the only reliable cure for anal fistula, with division of the traversed sphincter accepted as a necessary consequence; the functional cost of this approach was chronically underestimated. This critical narrative review, conducted in accordance with the SANRA criteria, confronts the historical dogma of radical fistulotomy with contemporary evidence and defines the current place of sphincter-sparing techniques in cryptoglandular and Crohn’s-related anal fistula. PubMed/MEDLINE, Scopus, Web of Science, the Cochrane Library and EMBASE were searched from 1 January 1990 to 30 April 2026, supplemented by the guidelines of international learned societies (ESCP, ASCRS, ECCO); randomised controlled trials, meta-analyses, systematic reviews, large prospective cohorts and official guidelines were eligible. Because no single anatomical threshold defines a complex fistula, explicit criteria combining tract anatomy, the proportion of external sphincter traversed, prior surgery and patient-level continence risk are set out at the outset and applied throughout; cryptoglandular and Crohn’s-related disease are considered separately in every technique section, since healing mechanisms, therapeutic objectives and eligibility for medical therapy differ substantially. High-resolution pelvic MRI and three-dimensional endoanal ultrasound have not replaced the Parks classification but have transformed the accuracy of anatomical mapping and operative planning, and show that 30% - 40% of fistulas are complex; in these, and particularly where additional risk factors coexist (anterior fistula in a woman, previous anal or obstetric sphincter injury, pre-existing continence impairment, chronic diarrhoea, Crohn’s disease), the functional cost of dividing the sphincter is generally judged unacceptable; the 2024 European Society of Coloproctology guidelines now enshrine sphincter preservation as the priority objective in complex disease. Ligation of the intersphincteric fistula tract achieves healing in approximately 80% with no reported incontinence in prospective series, and 96.2% when combined with a bioprosthetic plug in a selected cohort. Fistula laser closure, in a meta-analysis of 24 studies and 1503 patients, yields a primary healing rate of 57.5% (95% CI 49.4 - 65.3) with de novo incontinence of only 0.57% (0.00 - 2.15). Figures reported for other procedures derive from separate series that differ in case mix, in the definition of healing and in the instruments and timing used to assess continence, and are therefore reported here as descriptive safety profiles rather than head-to-head comparisons. Video-assisted anal fistula treatment achieves pooled healing of 76.0% but is now regarded principally as a diagnostic and preparatory tool. Mesenchymal stem cell therapy achieves pooled healing of 58.1% across heterogeneous cell products, doses and fistula phenotypes; the only licensed product, allogeneic expanded adipose-derived darvadstrocel, is indicated in complex perianal fistula of Crohn’s disease refractory to conventional or biological therapy, although the confirmatory ADMIRE CD II phase 3 trial did not meet its primary endpoint (48.8% versus 46.3% with placebo), and its use in cryptoglandular disease remains investigational. Radiofrequency thermocoagulation, by contrast, has shown healing rates of only 28% - 35% in the two published studies and cannot currently be recommended. The dogma of universal laying open belongs to the past: sphincter preservation is the default objective rather than one option among several in complex fistula, and therapeutic individualisation is the governing rule; the principal limitation of the sphincter-sparing techniques is not morbidity but primary failure and recurrence.