THE DIAGNOSTIC challenge of gastrointestinal bleeding is one that confronts physicians constantly. Even the most astute clinician aided by skillfully used radiographic and endoscopic procedures may be defeated in his search for the location and cause of a hemorrhage. The frequency with which the cause of gastrointestinal bleeding remains undiagnosed has been emphasized many times. In some series of carefully studied patients, failure to find the source of a hemorrhage has ranged from 15% to 40%.1-3 When bleeding has been characterized by melena without hematemesis inability to find the cause has been even more striking, as high as 52% in one series.4 Even surgical exploration frequently fails to disclose the cause of melena. Retzlaff et al5 reported that the source of the bleeding was discovered at operation in only 30% of a group of patients with melena.
Because of the need for greater accuracy in locating these