Factors affecting the detection of colorectal cancer and colon polyps on screening abdominal ultrasonography

The aim of this study was to identify factors affecting the detection of colorectal cancer (CRC) and colon polyps (CPs) using abdominal ultrasonography (US).Patient records were analyzed retrospectively. Those diagnosed as having either CRC or CPs by colonoscopy performed after screening abdominal US were enrolled. The diagnostic criterion for CRC was an irregularly thickened wall or mass. CPs were diagnosed as spherical or ovoid hypoechoic lesions arising within the colonic lumen as seen on abdominal US.Sixteen patients had a total of 16 CRC lesions and 11 patients had a total of 17 CPs. All CRC lesions invaded deeper than the subserosa. Cancer cell invasion limited to the submucosa was noted in the two 1.5-cm CPs. Detection of these lesions was not associated with invasion to lymph or blood vessels. These results suggest that wall thickening might be the consequence of cancer cells invading below the subserosa, thereby resulting in the lesions becoming detectable on abdominal US.Detection of CRC and CPs on abdominal US was associated with lesion size and depth of invasion.