Preoperative computed tomography measurement for predicting difficulty in hand-sewn ileal pouch-anal anastomosis: a refined single-center cohort study

Restorative proctocolectomy with a hand-sewn ileal pouch-anal anastomosis (IPAA) is a standard treatment for ulcerative colitis and familial adenomatous polyposis. However, achieving sufficient mesenteric length remains a significant challenge. This study aimed to validate the pouch extension distance (PED), a CT-based predictor for difficult ileal pouch extension specifically in planned hand-sewn IPAA. This refined retrospective cohort study was conducted at a single specialized academic institution. Fifty-seven consecutive patients undergoing total colectomy with a planned hand-sewn IPAA between 2008 and 2025 were included. The PED was measured on preoperative axial CT scans as the slice-to-slice distance from the junction of the ileocolic and marginal arteries to the anal verge. “Difficult pouch extension” (ED group) was defined as requiring the division of three or more mesenteric vessels or ligation of the ileocolic artery to achieve adequate reach. Clinical and anatomical factors were compared between the ED and normal groups. Seven patients (12.3%) were classified into the ED group. Difficult extension was significantly associated with higher body weight, higher BMI, higher serum albumin levels, familial adenomatous polyposis, and a longer PED. ROC analysis demonstrated that the PED possessed the highest predictive power (AUC 0.937). The optimal cut-off value for the PED was determined to be 21 cm. Preoperative PED measurement is a simple and highly accurate predictor of difficulty in achieving a tension-free hand-sewn IPAA. A PED of 21 cm or greater allows surgeons to optimize the surgical approach and prepare for advanced mesenteric lengthening maneuvers.