Background: Colonoscopy is an endoscopic tool for evaluation of colorectal cancer, and there is no conclusive evidence of a connection between clinical gut obstructions and obstructed endoscopy. Unplanned urgent operations in obstructed colorectal cancer by endoscopic processes may increase mortality and the possibility of poor outcome. The suitable waiting time to complete staging and prepare patients before surgery is not reported.

Objective: To determine suitable waiting times, incidence of emergency surgery during waiting times, and outcomes of obstructed colonoscopy.

Materials and Methods: Retrospective reviewed of obstructed colonoscopies in colorectal cancer was performed from medical records between January 2009 and December 2015. Patients who refused surgery or failed to attend follow-up appointments were excluded. Data were collected from both emergency and elective operation groups, including incidences of emergency surgery, waiting times, staging, level of obstruction, and outcome.

Results: Four thousand seventeen colonoscopies were performed in the surgical department at Ramathibodi Hospital between January 2009 and December 2015. There were 211 (5.25%) unsuccessful procedures due to tumor obstruction. Two hundred (4.97%) incomplete examinations were due to colorectal cancer obstruction and 11 (5.2%) obstructions were caused by other cancers. Twelve patients (7.3%) had emergency operations while waiting for surgery. The average waiting time was 25 days. No perioperative deaths were reported. The 5-year survival rate was lower in stage II and III.

Conclusion: The present study showed low incidence (7.3%) of emergency surgery in unsuccessful colonoscopy from obstructed colorectal cancer. Patients were able to wait two to three weeks after the date of incomplete colonoscopy without risk of increased mortality. Patients who had Stage II and Stage III colorectal cancer had poor prognostic factors.

Keywords: Endoscopic obstruction, Incomplete colonoscopy, Emergency surgery, Obstructed colorectal cancer