Investigation of Undetected Small Bowel Tumors on Capsule Endoscopy

AIM : The rate of undetected small bowel tumors when performing capsule endoscopy (CE) has been reported to be 44.1% to 83.3%. The aim of this study was to review the CE findings in patients with small bowel tumors and analyze the cases in which CE failed to detect tumors. METHODS : Twenty-one cases (18 males, 3 females) with small bowel tumors underwent CE and double-balloon enteroscopy at the Dokkyo Medical University Hospital and the Nikko Medical Center from February 2003 to March 2015. CE findings in the 21 patients were retrospectively reviewed on the basis of the lesion shape and location. RESULTS : Of the 21 patients, CE accurately diagnosed tumors in 12 patients (57.1%). However, tumors were not detected in 9 patients because of a poor endoscopic view due to visual obstruction caused by blood, bowel residue, or feces (n=5; 23.8%), the presence of ulcerated lesions (n=3; 14.3%), or angioectasia (n=1; 4.8%). The sources of bleeding were considered to be ulcerated lesions or angioectasia. Of the 9 patients, 7 patients had tumors in the duodenum or the proximal jejunum. CONCLUSION : On CE, small bowel tumors showed atypical features, including a smooth submucosal bulge and the presence of ulcerated lesions and of blood, bowel residue, or feces, probably due to regional transit abnormalities related to the tumor. In such cases, it may be necessary to perform computed tomography, positron emission tomography/computed tomography, other examinations, or repeat CE after performing colonic irrigation to remove bowel residue.