Impact of the body mass index on the retention of the anorectal mucosa after double-stapled ileal pouch-anal anastomosis for ulcerative colitis

BACKGROUND: Double-stapled ileal pouch-anal anastomosis (DS-IPAA) is easy to construct and has a good functional outcome in patients with ulcerative colitis (UC). However, retention of the anorectal mucosa may lead to a subsequent risk of inflammation and neoplasia. This study aimed to identify factors associated with the retention of a large amount of anorectal mucosa after DS-IPAA. METHODS: The medical records of 163 patients who had undergone one-stage total proctocolectomy and DS-IPAA for UC between 2007 and 2020 were retrospectively reviewed. The patients were divided into two groups according to the length of the retained mucosa. The high anastomosis group was defined as having a retained mucosal length of ≥ 30 mm in the anterior or posterior wall. Clinical factors were compared between the high and low anastomosis groups. RESULTS: The high anastomosis group showed a significantly higher body mass index (BMI) (high vs. low: 23.2 vs. 19.0), longer operation time (304 vs. 263) and greater blood loss (357 vs. 240). In the multivariate analysis, high BMI was the only factor significantly associated with high anastomosis (odds ratio 1.32). There was a positive correlation between BMI and the length of the retained mucosa. CONCLUSIONS: In DS-IPAA, BMI showed the strongest association with the retention of a large amount of the anorectal mucosa. In high BMI patients, although the risk of inability of anastomosis is little than that of IPAA with mucosectomy, the possible retention of a large amount of mucosa should be considered.