[Perception errors in detecting advanced colorectal cancers using a double-contrast enema]

The authors provide a didactic analysis of the errors in perception that can lead to false-negative findings in the detection of advanced rectocolonic cancers with double-contrast enema. They consider 5 categories of images as typical, ie. transverse or horizontal linear opacities, abnormal lumen due to haustral folds on semiaxial views, "pool sign", amputation of the cecum and irregular hypertrophy of the ileocolic valve. These mistakes will become exceptional if the double-contrast images are studied thoroughly using precise rules, and the percentage of false-negative findings in the detection of rectocolonic cancers should thus be reduced to 1%.