From the Guidelines
Oral contrast should not be administered to a patient with a suspected Gastrointestinal (G.I.) bleed undergoing a Computed Tomography (CT) scan of the abdomen, as it can interfere with the detection of active extravasation of blood into the GI tract. Instead, IV contrast is the preferred method for evaluating active GI bleeding, and a CT angiography protocol should be used, which involves IV contrast administration timed to the arterial phase to detect active bleeding 1. This approach typically includes a non-contrast phase followed by arterial and venous phases after IV contrast administration, allowing for the visualization of active extravasation, which appears as high-density material within the bowel lumen that changes in appearance or location on delayed images. The use of oral contrast can render the examination nondiagnostic, and oral administration of water can dilute intraluminal hemorrhage, making it less likely to detect the source of bleeding 1. Key considerations for the CT angiography protocol include:
- Non-contrast phase to detect intraluminal high-attenuation material
- Arterial phase to detect active bleeding
- Venous phase to detect slower bleeding rates
- Optional delayed phase (3-5 minutes after contrast administration) to detect slower bleeding rates if the bleeding source is unclear after initial imaging. By using IV contrast and a CT angiography protocol, the diagnostic yield can be maximized while avoiding unnecessary delays in patient management, ultimately improving outcomes in terms of morbidity, mortality, and quality of life for patients with suspected GI bleeding 1.
From the Research
Administration of Oral Contrast in CT Scans for G.I. Bleed
- The use of oral contrast in CT scans for patients with suspected Gastrointestinal (G.I.) bleed is not explicitly mentioned in the provided studies 2, 3, 4, 5, 6.
- However, the studies discuss the use of CT angiography (CTA) and CT enterography (CTE) in evaluating patients with G.I. bleeding 2, 3, 6.
- CTA is often used as an initial diagnostic test for acute G.I. bleeding, particularly in unstable patients 2, 6.
- CTE is frequently performed for suspected occult small bowel bleeding 2, 3.
- The sensitivity of CTA for detecting a source of G.I. bleeding is relatively low, suggesting that it should not be used as the sole initial diagnostic test 5.
- The role of oral contrast in CT scans for G.I. bleeding is not clearly defined in the provided studies, and its administration may depend on specific clinical scenarios and institutional protocols.
Key Findings
- CTA and CTE are valuable diagnostic tools in evaluating patients with G.I. bleeding 2, 3, 6.
- The choice of diagnostic test may depend on the patient's stability and the suspected location of the bleed 2, 6.
- Further research is needed to determine the optimal use of oral contrast in CT scans for patients with suspected G.I. bleed, as the current evidence does not provide clear guidance on this topic 2, 3, 4, 5, 6.