We would not want our review to lead to an abandonment of the radiologic examination of the colon. We view colonoscopy and barium enema examinations as complementary procedures—each technique is capable of detecting lesions missed by the other. If there is a gold standard in the diagnosis of colonic neoplasms, it must be the histopathologic findings. The advantage of colonoscopy is in obtaining tissue and, often, in effecting treatment simultaneously with the diagnosis. At our own medical center, barium studies precede colonoscopy, although there is ongoing debate regarding the value of the primary ACBE v the primary single-contrast barium enema. When planning the workup of the patient with GI tract bleeding of unknown origin, the clinician must ultimately consider the accuracy of the available diagnostic techniques as performed in his or her local hospital.