What is the diagnostic approach for gastrointestinal (GI) bleeding with or without contrast computed tomography (CT)?

From the Guidelines

For suspected gastrointestinal (GI) bleeding, CT scanning with intravenous contrast is the preferred initial imaging modality, as it allows for better visualization of active bleeding sites, vascular abnormalities, and potential causes of bleeding. The use of contrast-enhanced CT is supported by recent studies, including the 2024 consensus recommendations by the American College of Gastroenterology (ACG) and the Society of Abdominal Radiology (SAR) 1. According to the ACR Appropriateness Criteria, CTA with and without IV contrast can help detect the source of GI bleeding, with a sensitivity and specificity of 85% and 92%, respectively 1. Key benefits of contrast-enhanced CT include:

• Improved detection of active bleeding and vascular abnormalities
• Better visualization of potential causes of bleeding, such as tumors or inflammatory conditions
• Ability to guide subsequent interventional radiology, endoscopic, or surgical procedures In cases where contrast media is contraindicated, non-contrast CT or alternative imaging modalities like tagged red blood cell scintigraphy, angiography, or endoscopy may be considered 1. The typical protocol for contrast-enhanced CT involves administering 100-150 mL of iodinated contrast material intravenously at a rate of 3-5 mL/second, with imaging timed to the arterial and venous phases 1. For acute GI bleeding, a triple-phase CT (non-contrast, arterial, and venous phases) may be performed to maximize detection sensitivity 1. Overall, the use of contrast-enhanced CT as the initial imaging modality for suspected GI bleeding is supported by recent evidence and guidelines, and is recommended for its ability to provide accurate and timely diagnosis, and to guide subsequent management.

From the Research

Diagnostic Approaches for GI Bleed

• The diagnosis of gastrointestinal bleeding can be approached through various methods, including endoscopy, imaging techniques, and clinical evaluation 2, 3, 4.
• Endoscopy plays a major role in the diagnosis and treatment of acute GI bleeding, allowing for the application of hemostasis techniques during the diagnostic session 4.
• Imaging diagnostic techniques, such as CT angiography, scintigraphy with labeled erythrocytes, and arteriography, can be used to identify the location and cause of bleeding, especially in cases where endoscopy is not feasible 4, 5.

Role of CT Scan in GI Bleed Diagnosis

• CT scans can aid in identifying the location and cause of GI bleeding, and are an important complementary tool to endoscopy, nuclear medicine, and angiography in evaluating patients with GI bleeding 5.
• CT angiography can be used to diagnose GI bleeding, especially in cases of acute lower GI bleeding or when the bleeding is too brisk for endoscopy 3, 5.
• A CT reporting template can be used to help generate radiology reports that can add value to patient care, including the identification of common causes of GI bleeding and key patient history and risk factors 5.

Contrast CT in GI Bleed Diagnosis

• The use of contrast CT in GI bleed diagnosis can help identify the source of bleeding, especially in cases where endoscopy is not feasible or has failed to identify the source of bleeding 4, 5.
• Contrast CT can also be used to guide therapeutic interventions, such as arterial embolization, in cases where medical and endoscopic techniques have failed 4.