To evaluate the reliability of intrarectal contrast-enhanced ultrasonography in the detection of colorectal space-occupying lesions.

One hundred and ninety-six consecutive patients with suspected colonic and rectal lesions (colorectal cancer or colorectal polyps), who had undergone intrarectal contrast-enhanced ultrasonography and endoscopic evaluation, were enrolled in the study. Each examination was performed independently by two operators. Using surgical pathological findings as the gold standard, the accuracy of intrarectal contrast-enhanced ultrasonography was determined and compared with intestinal endoscopy.

After intrarectal contrast administration, the anatomy of the colon and rectum as well as the morphologic features of the lesions in these locations were clearly visualized. There were 81 cases of malignant lesions including colon cancer (n=39) and rectal cancer (n=42), and 30 cases of benign lesions including rectal polyps (n=11) and colonic polyps (n=19). The sensitivities, specificities, positive predictive values, negative predictive values and accuracies of intrarectal contrast-enhanced ultrasonography in detecting lesion site, size (>10 mm), number, and extents were similar to those of intestinal endoscopy. Moreover, intrarectal contrast-enhanced ultrasonography was far better than intestinal endoscopy in detecting adjacent structure abnormalities as identified at surgical pathology. However, intrarectal contrast-enhanced ultrasonography was a bit poorer than intestinal endoscopy in detecting minor mucosal abnormalities (<5 mm).

Intrarectal contrast-enhanced ultrasonography can effectively define the anatomic location and extension of colorectal space-occupying lesions, whose diagnostic performance is not worse than intestinal endoscopy. It can be used as a routine examination method for colorectal space-occupying lesions.