When to order computed tomography (CT) with intravenous (IV) contrast for suspected bleeding?

From the Guidelines

CT with IV contrast should be ordered for patients with suspected gastrointestinal bleeding when the source is unclear or when detailed vascular assessment is needed, as it can help detect bleeding rates as slow as 0.3 mL/min and has a sensitivity and specificity of 85% and 92%, respectively, for the diagnosis of active GIB 1. When to order CT with IV contrast for bleeding depends on various factors, including the patient's hemodynamic stability, significant hemoglobin drops, or clinical signs suggesting active hemorrhage.

• Specific indications for CT with IV contrast include:
  • Suspected gastrointestinal bleeding
  • Trauma with potential vascular injury
  • Neurological symptoms suggesting intracranial hemorrhage
  • Unexplained hematuria or retroperitoneal bleeding The contrast helps identify active extravasation of blood, vascular abnormalities, and enhances visualization of organs and vessels.
• Standard protocols typically use 80-120 mL of iodinated contrast injected at 3-5 mL/second, and before ordering, it is essential to check renal function (avoid with eGFR <30 mL/min), assess for contrast allergies, and ensure the patient is adequately hydrated 1. In emergency situations with life-threatening bleeding, the benefits of contrast-enhanced imaging usually outweigh the risks of contrast-induced nephropathy.
• A study evaluating different CT imaging protocols found that multiphasic CT protocols (unenhanced + arterial + portal venous phase) had the highest sensitivity of 92% for the detection of GIB compared with 83% for unenhanced phase with arterial or portal venous phase alone 1. Non-contrast CT may be preferred initially for suspected intracranial hemorrhage, while contrast-enhanced studies are better for identifying active bleeding in most body regions.
• The Society of Abdominal Radiology Gastrointestinal Bleeding Disease-Focused Panel published a consensus on CT imaging protocols for the detection of overt GIB, recommending noncontrast images for CTA performed on single-energy CT, which can be replaced by virtual noncontrast reconstructions with dual-energy CT 1.

From the FDA Drug Label

The decision to employ contrast enhancement, which may be associated with risk and increased radiation exposure, should be based upon a careful evaluation of clinical, other radiological, and unenhanced CT findings. A vascularized lesion is characterized by an increase in CT number in the few minutes after a bolus of intravascular contrast agent; it may be malignant, benign, or normal tissue, but would probably not be a cyst, hematoma, or other nonvascular lesion The answer to when to order a CT with IV contrast for bleeding is:

• When clinical and radiological evaluation suggests the presence of a vascularized lesion, such as active bleeding, and unenhanced CT findings are not sufficient for diagnosis.
• When differentiation between a vascularized lesion and a non-vascular lesion, such as a hematoma, is necessary. 2

From the Research

CT with IV Contrast for Bleeding

• The decision to order a CT with IV contrast for bleeding depends on various factors, including the type and severity of the bleeding, as well as the patient's overall condition 3, 4.
• Contrast-enhanced CT can help identify active bleeding by detecting contrast medium extravasation, which is a recognized sign of bleeding 3, 4.
• Different types of contrast agents can be used, including iohexol, iopamidol, and iodixanol, each with its own characteristics and potential advantages 5, 6, 7.
• The choice of contrast agent may depend on factors such as the patient's renal function, as well as the specific imaging protocol being used 7.
• Dual-bolus CT, which simultaneously opacifies both arterial and venous systems, can be useful in the diagnosis of active arterial bleeding in adult pelvic trauma 4.
• The accuracy of CT in diagnosing active bleeding can be high, but may vary depending on the specific scanning method and the experience of the radiologist interpreting the images 4.

Contrast Agents

• Iohexol and iopamidol are nonionic contrast media that have been compared in several studies, with similar efficacy and safety profiles 5, 6.
• Iodixanol is a dimeric nonionic contrast agent that has been shown to provide equal vascular enhancement compared to iohexol, despite having a lower iodine concentration 7.
• The choice of contrast agent may depend on the specific clinical scenario, as well as the patient's individual characteristics and medical history 5, 6, 7.

Imaging Protocols

• Contrast-enhanced sonography can be used to detect active bleeding, and may be a useful adjunct to CT in certain clinical scenarios 3.
• Dual-bolus CT can be used to simultaneously opacify both arterial and venous systems, and may be useful in the diagnosis of active arterial bleeding 4.
• The specific imaging protocol used may depend on the clinical question being asked, as well as the patient's individual characteristics and medical history 3, 4.