Efficacy of Preoperative Colonoscopy Following Self-Expandable Metallic Stent Placement in Patients with Obstructive Colorectal Cancer.

BACKGROUND: Obstructive colorectal cancer occurs in 8 to 13% of cases at diagnosis. Self-expandable metallic stents are increasingly used as a bridge to surgery to avoid emergency colostomy or ileostomy. However, whether preoperative total colonoscopy through a stent safely and effectively detect synchronous colorectal cancer remains unclear. OBJECTIVE: To evaluate the safety and efficacy of preoperative total colonoscopy following self-expandable metallic stents placement for detecting synchronous colorectal cancer in patients with malignant colonic obstruction. DESIGN: Single-center, retrospective study. SETTINGS: Chigasaki Municipal Hospital, Japan (ethics approval obtained from Yokohama City University Hospital). PATIENTS: Sixty-three consecutive patients (35 men, 28 women; median age: 75 years (range: 46-92years) who underwent self-expandable metallic stents placement as a bridge to surgery for obstructive colorectal cancer between April 2018 and November 2025. INTERVENTIONS: Self-expandable metallic stents placement under fluoroscopic and endoscopic guidance, followed by preoperative total colonoscopy attempted 48 to 72h after self-expandable metallic stents placement once bowel obstruction resolved. MAIN OUTCOME MEASURES: Primary - detection rate of synchronous colorectal cancer. Secondary - technical and clinical success of self-expandable metallic stents, total colonoscopy completion rate, and procedure-related complications. RESULTS: Self-expandable metallic stents placement was technically successful in 62 of 63 patients (98.4%), with clinical resolution of obstruction in 60 of 63 (95.2%). Preoperative total colonoscopy was attempted in 53 of 60 patients (88.3%) and completed in 43 of 53 (81.1%), yielding an overall completion rate of 68.3% (43 of 63). Synchronous colorectal cancer was detected preoperatively in 8 of 43 patients (18.6%), altering surgical strategy. No complications related to preoperative total colonoscopy occurred. Limitations: Retrospective, single-center design with a small sample size; only uncovered self-expandable metallic stents types were used, limiting generalizability. CONCLUSIONS: Preoperative total colonoscopy after self-expandable metallic stents placement is a safe and effective method for detecting synchronous colorectal cancer and optimizing surgical planning in obstructive colorectal cancer. Whenever feasible, total colonoscopy should be considered for patients undergoing self-expandable metallic stents as a bridge to surgery. See Video Abstract.