Preoperative colonoscopy through the colonic stent in patients with colorectal cancer obstruction

AIM:To evaluate the feasibility of a preoperative colonoscopy through a self-expendable metallic stent(SEMS)and to identify the factors that affect complete colonoscopy.METHODS:A total of 48 patients who had SEMS placement because of acute malignant colonic obstruction underwent preoperative colonoscopy.After effective SEMS placement,patients who showed complete resolution of radiological findings and clinical signs of acute colon obstruction underwent a standard bowel preparation.Preoperative colonoscopy was then performed using a standard colonoscope.If the passage of colonoscope was not feasible gastroscope was used.After colonoscopy,cecal intubation time,grade of bowel preparation,tumor location,stent location,presence of synchronous polyps or cancer,damage to colonoscopy and bleeding,and stent migration after colonoscopy were recorded.RESULTS:Complete evaluation with colonoscope was possible in 30 patients(62.5%).In this group,adenoma was detected in 13 patients(43.3%).The factors that affected complete colonoscopy were also analyzed:Tumor location at an angle;stent placement at an angle;and stent expansion diameter,which affected complete colonoscopy significantly.However in multivariate analysis,stent expansion diameter was the only significant factor that affected complete colonoscopy.Complete evaluation using additional gastroscope was feasible in 42 patients(87.5%).CONCLUSION:Preoperative colonoscopy through the colonic stent using only conventional colonoscope was unfavorable.The narrow expansion diameter of the stent may predict unfavorable outcome.In such a case,using small caliber scope should be considered and may expect successful outcome.