Cutting of the Intersphincteric Space for High Anal Fistula: Functional Preservation and a Predictive Model for Postoperative Anal Incontinence
Related Experiment Video
Updated: Mar 3, 2026
Author Spotlight: Developing a Rat Model for Pouchitis Research and Treatment
Published on: May 31, 2024
Jiawei Qin1, Yanyan Tan, Xueping Zheng
1Department of Colorectal Surgery, Nanjing Hospital of Chinese Medicine affiliated to Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China.
Insights
The Cutting of the Intersphincteric Space (COIS) procedure offers effective treatment for high anal fistulas, balancing cure rates with sphincter preservation. A predictive model using gender, age, and neutrophil ratio aids in assessing functional decline risk post-surgery.
Area of Science:
- Colorectal Surgery
- Surgical Innovation
- Patient Outcomes
Background:
- High anal fistula (HAF) management is challenging due to high recurrence and incontinence risks.
- Sphincter-preserving techniques are crucial for maintaining anal function post-treatment.
- Assessing effectiveness and predicting functional decline are key for HAF treatment optimization.
Purpose of the Study:
- To evaluate the effectiveness of the Cutting of the Intersphincteric Space (COIS) procedure for HAF.
- To develop a predictive model for postoperative functional decline after COIS.
- To identify predictors of anal functional status changes post-COIS.
Main Methods:
- Prospective single-center cohort study of 146 HAF patients undergoing COIS.
- 18-month follow-up assessing anal functional status via Wexner incontinence score.
- Multivariate logistic regression identified predictors of functional decline; a nomogram was developed.
Main Results:
- COIS demonstrated a low recurrence rate (4.8%) and acceptable functional outcomes.
- 11.6% of patients experienced significant anal functional decline.
- Gender, age, and neutrophil ratio (NR) were independent predictors of functional decline (AUC = 0.739).
Conclusions:
- COIS is a functionally optimized approach for HAF, preserving sphincter integrity while achieving radical cure.
- A predictive model integrating gender, age, and NR enhances personalized risk assessment for functional decline.
- This approach shifts HAF management towards function-preserving strategies, emphasizing metabolic and inflammatory profiling.
Background:
Management of high anal fistula (HAF) remains challenging due to risks of recurrence and anal incontinence. This study was undertaken to assess the effectiveness of the cutting of the intersphincteric space (COIS) in HAF and to develop a predictive model for postoperative functional decline.
Study Design:
A prospective single-center cohort study of 146 consecutive patients with HAF who underwent COIS at the Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine from January 2021 to July 2024, with an 18-month follow-up was conducted. COIS is a sphincter-preserving technique targeting intersphincteric space dissection to maintain anal sphincter integrity. The primary outcome was the change in anal functional status, measured by the Wexner incontinence score, at 3 months postoperatively. Secondary outcomes included recurrence rate and identification of independent predictors of functional decline via multivariate logistic regression.
Results:
Significant anal functional decline occurred in 11.6% (17 of 146) of patients, with a recurrence rate of 4.8%. Sex, age, and neutrophil ratio were independent predictors of functional decline (area under the curve 0.739, 95% CI 0.645 to 0.833). A nomogram incorporating these biomarkers demonstrated excellent calibration and clinical use. Single-center design may limit generalizability; external validation in multicenter cohorts is warranted.
Conclusions:
COIS represents a functionally optimized approach for HAF, balancing radical cure and sphincter integrity. The predictive model integrating systemic biomarkers advances personalized risk assessment, guiding surgical decision-making for patients prioritizing continence. These findings underscore the importance of metabolic and inflammatory profiling in prognostication, shifting the paradigm from anatomy-driven to function-preserving strategies.
