Objective To analyze the risk of postoperative ileus in severe ulcerative colitis (UC) patients undergoing total proctocolectomy with ileal pouch-anal anastomosis (TPC-IPAA) and develop and validate a nomogram prediction model.

Methods A total of 278 severe UC patients undergoing TPC-IPAA from January 2018 to May 2022 were enrolled and divided into ileus group (n=73) and non-ileus group (n=205) based on the occurrence of postoperative ileus. Another 120 severe UC patients undergoing TPC-IPAA from June 2022 to April 2023 were selected as validation cohort (with a 7-to-3 ratio between the modeling cohort and the validation cohort). Factors influencing postoperative ileus in severe UC patients undergoing TPC-IPAA were analyzed to construct a Nomogram prediction model. The discrimination, consistency, and clinical utility of the Nomogram model were evaluated by the receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA).

Results There were no significant differences in general characteristics between the modeling cohort and the validation cohort (P>0.05). Significant differences were observed in preoperative American Society of Anesthesiologists (ASA) classification, preoperative albumin level, history of abdominal surgery, surgical approach, operation duration, intraoperative blood loss, and postoperative intra-abdominal infection between the ileus group and the non-ileusgroup (P < 0.05). Preoperative ASA classification, preoperative albumin level, history of abdominal surgery, operation duration, intraoperative blood loss, and postoperative intra-abdominal infection were independent influencing factors for postoperative ileus in severe UC patients undergoing TPC-IPAA (P < 0.05). The ROC curve showed that the area under the curve of the Nomogram model for predicting postoperative ileus in severe UC patients undergoing TPC-IPAA was 0.782 (95%CI, 0.723 to 0.842) in the modeling cohort and 0.785 (95%CI, 0.693 to 0.878) in the validation cohort, indicating good discrimination of the model. The calibration curve demonstrated good consistency of the nomogram model. The DCA curve suggested high clinical utility of the Nomogram model.

Conclusion The risk of postoperative ileus in severe UC patients undergoing TPC-IPAA is influenced by preoperative ASA classification, history of abdominal surgery, preoperative albumin level, intraoperative blood loss, operation duration, and postoperative intra-abdominal infection. The nomogram prediction model developed based on these factors has high predictive performance for the risk of postoperative ileus.