17 - Middle Gastrointestinal Bleeding

Abstract

Obscure gastrointestinal (GI) bleeding accounts for approximately 5% of all GI bleeding and has been defined as bleeding from an unknown source that persists or recurs after negative bidirectional endoscopic diagnostic evaluations (e.g., negative esophagogastroduodenoscopy and ileocolonoscopy). With the introduction of video capsule endoscopy and device-assisted deep enteroscopy, as well as the newfound ability to endoscopically visualize the entire length of the small bowel, the majority of patients who were previously classified as having obscure GI bleeding were actually found to have a small bowel source of bleeding. Thus, small bowel bleeding is now referred to as middle GI bleeding if the source of bleeding is located between the ligament of Treitz and the ileocecal valve. Thus today, following negative upper and lower endoscopic examinations and before performance of video capsule endoscopy, patients should be classified as having “suspected middle GI bleeding” with the diagnosis of true obscure GI bleeding reserved only for patients who have also undergone a negative endoscopic evaluation of the entire small bowel. This chapter will review the possible causes of middle GI bleeding and what diagnostic investigations are available including: endoscopy, small bowel contrast radiography, cross-sectional imaging, nuclear medicine studies, and angiography. We also propose an evidence-based diagnostic strategy for the evaluation of middle GI bleeding and provide numerous demonstrative endoscopic images and video clips.