Detection of Gastrointestinal Bleeding Sites: Use of In Vitro Technetium Tc 99m—Labeled RBCs

Sixteen patients clinically suspected of having gastrointestinal hemorrhage were studied by abdominal scintigraphy with RBCs labeled in vitro with technetium Tc 99m. Ten of 11 actively bleeding patients had positive scintigrams, with bleeding localized to the duodenum in one, ascending colon in five, sigmoid colon in six, and rectosigmoid colon in one. Scintigraphic findings were corroborated by clinical, endoscopic, arteriographic, and surgical findings. Retention of this blood-pool radiotracer in the vascular compartment allows noninvasive diagnosis of acute, as well as slow or intermittent, bleeding for up to 24 hours after intravenous administration. ( JAMA 1982;247:789-792)