Guideline Recommendations for Anal Fistulotomy: Evidence‑Based Risks and Management
Anal Sphincter Physiology
- The internal anal sphincter generates the majority of resting anal pressure, providing the basal tone that maintains continence, whereas voluntary squeeze pressure is produced primarily by the external anal sphincter. 1
Patient‑Specific Risk Factors
- Individuals with Crohn’s disease exhibit significantly higher resting anal pressures (approximately 114 cm H₂O) compared with healthy controls (≈ 73 cm H₂O), which may affect surgical outcomes. 4
- High‑risk anatomy includes an anterior fistula location in women, pre‑existing sphincter defects, and underlying inflammatory bowel disease; these factors increase the likelihood of postoperative incontinence. [2][3]
Surgical Technique Risks
- Performing an anterior fistulotomy in women should be avoided because women have a shorter anterior sphincter length and smaller external sphincter volume, making them more vulnerable to continence loss. [2][3]
- The use of cutting setons is contraindicated; they cause forced sphincter migration and are associated with a 57 % risk of postoperative incontinence. [2][3]
- Manual anal dilatation should not be employed, as it results in permanent incontinence in 10–30 % of patients. [4][1]
- In patients with complex perianal Crohn’s disease, fistulotomy leads to keyhole deformity and high rates of incontinence; therefore, fistulotomy is discouraged in this population. [2][3]