Value of 3D ‐High Resolution Anorectal Manometry Before and After Fistulotomy for Simple Perianal Fistulas: A Prospective Cohort Study

AIM: Surgical treatment of perianal fistulas is challenging due to the risk of postoperative fecal incontinence, which can significantly impair quality of life. Fistulotomy is commonly used as an effective treatment for simple fistulas with limited sphincter involvement, assuming a minimal risk of continence deterioration. However, partial sphincter division may still affect anorectal pressures. This study prospectively evaluates changes in anal sphincter function using three-dimensional high resolution anorectal manometry (3D-HRAM) alongside continence and quality of life outcomes before and after fistulotomy. METHODS: A prospective single-center cohort study was conducted at a tertiary referral center in the Netherlands. Adults undergoing fistulotomy for simple perianal fistulas were included. Pre- and postoperative assessments included clinical evaluation, 3D-endoanal ultrasound, 3D-HRAM, and functional outcome measures for fecal incontinence and quality of life. Long-term outcomes were assessed via standardized questionnaires at 12 months postoperatively. Primary outcomes were changes in anorectal pressures, continence deterioration, and quality of life. RESULTS: Among 47 patients, 26% experienced continence deterioration despite unchanged mean sphincter pressures postoperatively. This subgroup showed lower preoperative fistula tract pressures and altered voluntary squeeze pressures on 3D-HRAM. Despite this, overall quality of life improved significantly following fistula healing. CONCLUSION: 3D-HRAM allows for regional pressure mapping in perianal fistula but does not reliably predict continence deterioration after fistulotomy. Given the low risk of severe incontinence, routine preoperative 3D-HRAM is not warranted for simple fistulas. Future research should refine continence assessment and clarify its role in complex fistulas, where the risk impairment is higher. TRIAL REGISTRATION: Dutch trial register: NL78713.018.21.