Risk factors for postoperative stoma outlet obstruction in ulcerative colitis

BACKGROUND Current medical treatments can achieve remission of ulcerative colitis (UC). Surgery is required when potent drug treatment is ineffective or when colon cancer or high-grade dysplasia develops. The standard procedure is restorative proctocolectomy (RPC) with ileal pouch-anal anastomosis, commonly performed as two- or three-stage RPC with diverting ileostomy. Postoperative stoma outlet obstruction (SOO) is frequent, but the causes are not well known. AIM To identify the risk factors for SOO after stoma surgery in patients with UC. METHODS We retrospectively reviewed the files of 148 consecutive UC patients who underwent surgery with stoma construction. SOO was defined as small bowel obstruction symptoms and intestinal dilatation just below the penetrating part of the stoma on computed tomography. Patients were divided into two groups: Those who developed SOO within 30 d after surgery and those who did not. Patient characteristics, intraoperative parameters, the stoma site, and rectus abdominis muscle thickness were collected. Moreover, we identified the patients who repeatedly developed SOO. Univariate and multivariate analyses were performed to identify risk factors for SOO and recurring SOO. RESULTS Eighty-nine patients who underwent two-stage RPC were included between January 2008 and March 2020. Postoperatively, SOO occurred in 25 (16.9%) patients after a median time of 9 d (range 2-26). Compared to patients without SOO, patients with SOO had a significantly higher rate of malignant tumors or dysplasia (36.0% vs 17.1%, P = 0.032), lower total glucocorticoid dose one month before surgery (0 mg vs 0 mg, P = 0.026), higher preoperative total protein level (6.8 g/dL vs 6.3 g/dL, P = 0.048), higher rate of loop ileostomy (88.0% vs 55.3%, P = 0.002), and higher maximum stoma drainage volume (2300 mL vs 1690 mL, P = 0.004). Loop ileostomy (OR = 6.361; 95%CI 1.322-30.611; P = 0.021) and maximum stoma drainage volume (OR = 1.000; 95%CI 1.000-1.001; P = 0.015) were confirmed as independent risk factors for SOO. Eighteen patients with SOO were treated conservatively without recurrence (sSOO group). Seven (28.0%) patients repeatedly developed SOO (rSOO group) during the observation period. A significant difference was observed in the rectus abdominis muscle thickness between the two groups (sSOO 9.3 mm, rSOO 12.7 mm, P = 0.006). Muscle thickness was confirmed as an independent risk factor for recurring SOO (OR = 2.676; 95%CI 1.176-4.300; P = 0.008). CONCLUSION In this study, high maximum stoma drainage volume and loop ileostomy are independent risk factors for SOO. Additionally, among patients with a thick rectus abdominis muscle, the risk of SOO recurrence is high.