Diagnostic Role of Radiology in Acute Gastrointestinal Bleeding: A Comprehensive Review.

Acute gastrointestinal bleeding (GIB) is a major medical emergency with high morbidity and mortality. Endoscopy remains the first-line diagnostic and therapeutic approach, but radiological imaging has become increasingly important, particularly when endoscopy is inconclusive or unavailable. This review outlines the evolving role of radiological techniques, including computed tomography angiography (CTA), catheter-based angiography, radionuclide scintigraphy, magnetic resonance imaging (MRI), and ultrasound (US), in the detection, localization, and management of acute GIB. CTA is now the preferred imaging modality because of its speed, noninvasive nature, and superior anatomical detail. Catheter angiography not only enables precise diagnosis but also provides therapeutic options through embolization. Nuclear medicine techniques offer high sensitivity for intermittent or low-rate bleeding, while MRI and US contribute complementary insights in select patient groups. An integrated approach that combines radiological, endoscopic, and surgical strategies improves decision-making, shortens time to intervention, and enhances patient outcomes. Recent advances, including dual-energy CT, AI-assisted imaging, and novel embolic agents, are expected to further strengthen both diagnostic accuracy and therapeutic potential. Understanding the strengths, limitations, and sequencing of these modalities is key to optimizing care for patients with acute GIB.