Is a computed tomography (CT) scan with contrast or without contrast indicated for a patient with a gastrointestinal (GI) bleed?

From the Guidelines

For a suspected gastrointestinal (GI) bleed, a computed tomography (CT) scan with intravenous contrast is the recommended initial imaging modality, as it allows for better visualization of active bleeding sites, vascular abnormalities, and potential causes of hemorrhage. The use of contrast-enhanced CT scanning is supported by recent studies, including a 2024 consensus recommendation published in Radiology, which highlights the advantages of CT angiography (CTA) in evaluating patients with overt GI bleeding 1.

Key Considerations

• The contrast-enhanced CT scan enables the detection of intraluminal blood products or active contrast material extravasation, localizing the site of hemorrhage and identifying etiologies outside of the GI tract.
• CT techniques such as digital subtraction and dual-energy acquisition have improved the ability of CT to detect subtle GI tract lesions.
• A multiphasic approach, including arterial and venous phases, is typically used to maximize detection of bleeding sources, as recommended by the Society of Abdominal Radiology Gastrointestinal Bleeding Disease-Focused Panel 1.
• Non-contrast CT may still be useful in detecting large hematomas or masses, but its sensitivity is lower compared to contrast-enhanced CT.

Alternative Imaging Modalities

• In cases where contrast is contraindicated, such as severe renal impairment or contrast allergy, alternative imaging modalities like tagged red blood cell scans or angiography might be considered instead 1.
• The timing of the scan is crucial, and it should be performed while bleeding is active to increase the likelihood of detecting the bleeding source.

Evidence-Based Recommendation

• A recent meta-analysis of 22 studies evaluating the accuracy of CTA for the diagnosis of active GI bleeding found that CTA had a sensitivity and specificity of 85% and 92%, respectively 1.
• The use of CTA as the first test leads to faster triage of patients in the emergency room when compared with endoscopy for GI bleed 1.

From the Research

Computed Tomography (CT) Scan for Gastrointestinal (GI) Bleed

• A CT scan with contrast is indicated for a patient with a gastrointestinal (GI) bleed, as it can help identify the location and cause of bleeding 2, 3, 4.
• CT angiography is a useful diagnostic tool for evaluating GI bleeding, especially in unstable patients or when endoscopy is not feasible 5, 3.
• The use of contrast in CT scans can enhance the visualization of the bleeding site and surrounding structures, aiding in the diagnosis and management of GI bleeding 2, 4.
• CT enterography is also a valuable diagnostic tool for evaluating occult small bowel bleeding, which accounts for 5-10% of GI bleeding cases 3, 4.

Diagnostic Approach

• The diagnostic approach to GI bleeding typically involves a combination of clinical evaluation, laboratory tests, and imaging studies, including CT scans and endoscopy 5, 6.
• Clinical prediction guides, such as the Glasgow-Blatchford bleeding score, can help stratify patients with upper GI bleeding and determine the need for urgent endoscopy 6.
• Endoscopy plays a major role in the diagnosis and treatment of acute GI bleeding, and CT scans can be used as a complementary tool to guide further management 5, 6.

Imaging Techniques

• CT angiography and CT enterography are commonly used imaging techniques for evaluating GI bleeding, with CT angiography being preferred for initial evaluation in unstable patients 3.
• The use of multiphase CT enterography can help identify the source of bleeding in patients with occult small bowel bleeding 3.
• A CT reporting template can be used to generate radiology reports that add value to patient care, including the description of the bleeding site, cause, and surrounding structures 4.