What is the best initial CT (Computed Tomography) abdomen study to assess for upper Gastrointestinal (GI) bleed?

From the Guidelines

The best initial CT abdomen study to assess for upper gastrointestinal bleeding is a multiphasic CT angiography (CTA) with both arterial and venous phases, as it can detect bleeding rates as low as 0.3 mL/min and provides detailed anatomic information about potential bleeding sources. This study should be performed without oral contrast but with intravenous contrast administered at a high injection rate (typically 4-5 mL/second) 1. The protocol should include a non-contrast phase followed by arterial phase imaging (approximately 20-30 seconds after contrast injection) and portal venous phase imaging (60-70 seconds after injection). For optimal results, the patient should be adequately hydrated and have normal renal function to safely receive the contrast.

Key Considerations

• The use of multiphasic CT protocols (unenhanced + arterial + portal venous phase) has been shown to have the highest sensitivity of 92% for the detection of GIB compared with 83% for unenhanced phase with arterial or portal venous phase alone 1.
• CTA has been shown to be able to detect bleeding rates as slow as 0.3 mL/min, compared with 0.5 to 1.0 mL/min for conventional angiography and 0.2 mL/min for Tc-99m–labeled red blood cell (RBC) scintigraphy 1.
• The noncontrast images are useful for the detection of intraluminal high-attenuation material that may mimic intraluminal blood on contrast-enhanced images and may be necessary for the identification of sentinel clot 1.

Benefits of CTA

• CTA is widely available and can be performed rapidly during the time of bleeding, which may aid in detection compared with other techniques 1.
• CTA provides detailed anatomic information about potential bleeding sources such as angiodysplasias, tumors, or vascular malformations.
• The multiphasic technique is crucial because bleeding may be intermittent, and capturing both arterial and venous phases increases the likelihood of detecting the bleeding source, which guides subsequent management decisions including potential endoscopic or interventional radiology procedures.

From the FDA Drug Label

OMNIPAQUE diluted to concentrations from 6 mg Iodine/mL to 9 mg Iodine/mL administered orally in conjunction with OMNIPAQUE 300 at a concentration of 300 mg Iodine/mL administered intravenously are indicated in adults for use in contrast enhanced computed tomography of the abdomen Dilute oral plus intravenous OMNIPAQUE may be useful when unenhanced imaging does not provide sufficient delineation between normal loops of the bowel and adjacent organs or areas of suspected pathology.

The best initial CT abdomen study to assess for upper GI bleed is a contrast-enhanced CT using oral and intravenous OMNIPAQUE. The recommended oral dosage is 500 mL to 1000 mL of OMNIPAQUE diluted to concentrations of 6 mg Iodine/mL to 9 mg Iodine/mL, administered about 20 to 40 minutes prior to the intravenous dose and image acquisition. The recommended intravenous dosage is 100 mL to 150 mL of OMNIPAQUE 300 2.

• Key points:
  • Oral dosage: 500 mL to 1000 mL of OMNIPAQUE diluted to 6 mg Iodine/mL to 9 mg Iodine/mL
  • Intravenous dosage: 100 mL to 150 mL of OMNIPAQUE 300
  • Administration: Oral dose 20 to 40 minutes prior to intravenous dose and image acquisition

From the Research

Initial CT Abdomen Study for Upper GI Bleed

The best initial CT abdomen study to assess for upper GI bleed is a topic of interest in the medical field.

• CT angiography (CTA) is a promising initial test for acute GI bleeding as it is universally available, can be performed rapidly, and may provide diagnostic information to guide management 3.
• The diagnostic performance of CTA in identifying the cause of bleeding has been investigated, and it has been found to have a fairly high accuracy, with a sensitivity of 84.8% and a positive predictive value of 98.5% 4.
• The use of multi-detector row CT in an experimental setup has also been evaluated, and it has been found that the combination of arterial and portal venous acquisitions provides the highest sensitivity and specificity in the detection of intestinal bleeding 5.
• Helical CT imaging using rapid infusion of intravenous contrast and water as oral contrast has also been found to be a useful noninvasive alternative study to consider when routine work-up fails to determine the cause of active GI bleeding 6.
• A pictorial review has been provided to aid radiologists in interpreting GI bleeding CT studies, which includes the proper GI bleeding terminology, the most common causes of GI bleeding, key patient history and risk factors, the optimal CT imaging technique, and guidelines for case interpretation 7.

Key Findings

• CTA is a useful initial test for acute GI bleeding.
• The combination of arterial and portal venous acquisitions provides the highest sensitivity and specificity in the detection of intestinal bleeding.
• Helical CT imaging can be a useful noninvasive alternative study to consider when routine work-up fails to determine the cause of active GI bleeding.
• A pictorial review can aid radiologists in interpreting GI bleeding CT studies.

CT Imaging Techniques

• CTA is a promising initial test for acute GI bleeding.
• Multi-detector row CT can be used to detect intestinal bleeding.
• Helical CT imaging can be used to detect obscure GI bleeding.