A primer on the imaging approach to acute gastrointestinal bleeding

Acute gastrointestinal bleeding (GIB) is a common cause of emergency department presentation, with outcomes ranging from self-limited bleeding to potentially life-threatening hemorrhage. Based on location, acute GIB can be broadly categorized as upper gastrointestinal bleeding (UGIB), lower gastrointestinal bleeding (LGIB), or small-bowel bleeding (SBB). Understanding the clinical presentation and laboratory findings can help determine the appropriate next step in diagnostic evaluation and management. Imaging and endoscopy form the mainstay of evaluation and treatment. Multiphasic CT angiography (CTA), technetium-99 m–labeled red blood cell (RBC) scintigraphy, and catheter angiography are key imaging modalities in the workup of acute GIB. Recognition of common causes, appropriate modality selection, protocol optimization, and awareness of key interpretive pearls and pitfalls are essential for accurate radiologic interpretation and reporting, ultimately improving patient outcomes.