Detection and localization of lower gastrointestinal bleeding site with scintigraphic techniques

Successful management of acute gastrointestinal (GI) bleeding frequently depends on accurate localization of the bleeding site. History and clinical findings are often misleading in localizing the site of hemorrhage. The widespread application of flexible endoscopy and selective arteriography now provides accurate diagnoses for the majority of patients with upper GI tract hemorrhage, but lower GI bleeding still is a serious diagnostic problem. Endoscopy and barium studies are of limited value in examining the small bowel and colon in the face of active hemorrhage. Arteriography, although successful in many cases, has limitations. The angiographic demonstration of bleeding is possible only when the injection of contrast material coincides with active bleeding. Since lower GI bleeding is commonly intermittent rather than continuous, a high rate of negative angiographic examinations has been reported. Repeated angiography to pursue recurrent episodes of bleeding is impractical. Because of these shortcomings, in the past decade several noninvasive scintigraphic techniques have been developed to detect and localize sites of GI bleeding. In this chapter the authors discuss details related to the technetium 99m sulfur colloid (Tc-SC) and technetium 99m-labeled red blood cell (Tc-RBC) techniques