Objective To summarize the occurrence of anal fistula in Crohn disease (CDAF) accompanying with preoperative rectal stenosis and analyze its influencing factors. Meanwhile to explore the effect of improved anal sphincter retention virtual-hanging (hereafter this text will be abbreviated as virtual-hanging) for treatment of CDAF. Methods The CDAF patients admitted to the Third People’s Hospital of Bengbu from January 2019 to June 2021 were retrospectively collected, who were treated with virtual-hanging. Meanwhile the multivariable logistic regression analysis was used to identify the risk factors for accompanying with preoperative rectal stenosis and which were used to establish a decision tree model by Chi squared automatic interaction detection method. Results A total of 234 patients with CDAF were collected, and the incidence of accompanying with preoperative rectal stenosis was 22.2% (52/234). The multivariate logistic regression analysis found that the patients with preoperative proctitis, Montreal subtype B2, fistula located above the musculi levator ani (MLA), single fistula accompanied by branches or multiple fistulas, lymphocyte count (Lym) ≥6.03×10⁹/L, platelet count (PLT) ≥0.61×10⁹/L, erythrocyte sedimentation rate (ESR) ≥39.11 mm/h, C-reactive protein (CRP) ≥5.13 mg/L, and brain natriuretic peptide (BNP) ≥313.26 ng/L had higher probability of accompanying with preoperative rectal stenosis (P<0.05). For the patients with or without preoperative rectal stenosis, the CD activity index score and perianal CD activity index score, and anal resting pressure all showed decreasing trends after treatment with the virtual-hanging, and the anal maximal contraction pressure showed a increasing trend as compared to before treatment. The decision tree consisted 18 nodes and 9 terminal nodes. The gain map of the decision tree model gradually increased from 0% to 100%; The index chart maintained a high level starting from 198% and then rapidly decreased to 100%. The area under the receiver operating characteristic curve of the decision tree model was 0.852 [95%CI (0.821, 0.908)], with a sensitivity of 84.35% and a specificity of 82.33%. Conclusions The incidence of accompanying with preoperative rectal stenosis in patients with CDAF is relatively higher. The effect of virtual-hanging for treatment of CDAF is better. For patients with preoperative proctitis, Montreal subtype B2, fistula above the MLA, single fistula accompanied by branches or multiple fistulas, and higher Lym, PLT, ESR, CRP, and BNP, attention should be paid to their accompanying with preoperative rectal stenosis. The decision tree model based on these factors to distinguish whether accompanying with preoperative rectal stenosis is better.

Citation： WU Jun, XIANG Wujun, CHEN Zhenyu. Efficacy of improved anal sphincter retention virtual-hanging in treating anal fistula in Crohn disease and analysis of factors affecting preoperative rectal stenosis. CHINESE JOURNAL OF BASES AND CLINICS IN GENERAL SURGERY, 2024, 31(7): 863-869. doi: 10.7507/1007-9424.202311094 Copy