Polypoid lesions of the sigmoid colon: a comparison of single-contrast, double-contrast, and biphasic examinations.

The single-contrast (SC), double-contrast (DC), and biphasic examinations of the sigmoid colon in 51 patients with histologically proved sigmoid polyps 1.0 cm or greater in diameter were reviewed. In each case the polyps were radiographically detected and visualized by endoscopy. The radiographs of 49 patients without sigmoid polyps were similarly reviewed. The biphasic approach was significantly superior to the single-contrast examination in the detection of sigmoid polyps (p less than 0.05). The differences between SC and DC examinations as well as between DC and biphasic examinations were not significant. In the presence of diverticulosis, however, the biphasic approach proved to be significantly more sensitive than the DC examination. The greater sensitivity of the biphasic examination compared with SC was of borderline significance. It is concluded that in the presence of diverticulosis a combination of single- and double-contrast techniques can improve the sensitivity of the examination significantly in the detection of polypoid lesions.