Usefulness and limitations of transabdominal ultrasonography for detecting small-bowel tumors

New methods of examining the small bowel, e.g. capsule endoscopy (CE) and double-balloon endoscopy (DBE), have recently been developed. Transabdominal ultrasonography (TUS) is a conventional, non-invasive, and less-expensive modality. The aim of this study was to evaluate the usefulness and limitations of TUS for the detection of small-bowel tumors.

A total of 371 patients who underwent CE and/or DBE were enrolled in the study. All patients underwent TUS prior to CE and DBE. We evaluated the sensitivity and specificity of TUS in detecting small-bowel tumors, diagnosis and size of tumors, overall detection rate of tumors by TUS, detection rate according to tumor size and shape, and the ultrasonographic features of the tumors.

The sensitivity and specificity rates of TUS were 26.4% and 98.6%, respectively. A total of 92 tumors detected by CE and/or DBE were analyzed. Mean size of small-bowel tumors was 20.0 mm. The detection rate of TUS was 25.0%; the detection rate for tumors smaller than 20 mm was only 1.8%, while that for tumors of 20 mm or larger was 59.5%. Despite the tumor size being 20 mm or larger, none of the granular lateral spreading lesions were detected by TUS, but all of the circumferential ulcerative lesions could be detected using this procedure.

TUS is considered to be a useful modality for detecting small-bowel lesions of large volume. We consider that TUS is the first choice modality for examining small-bowel lesions because it is a non-invasive and non-expensive procedure that can detect large lesions.