[Profile projection of the rectosigmoid in left lateral decubitus with vertical rays in the diagnosis of obstruction of the lower colon].

For differential diagnosis between obstruction of the lower organ and paralytic ileus, an additional projection to the customary A.S.P. plates is proposed: profile of the rectosigmoid in left lateral decubitus with vertical rays, designed to back up the differential reasoning behind the presence or absence of a rectosigmoid distended by gas.