From the Guidelines
For patients with gastrointestinal bleeding (GIB), computed tomography angiography (CTA) is the preferred initial imaging modality due to its faster results, better anatomical localization, and ability to detect bleeding rates of approximately 0.3-0.5 mL/min, as supported by the most recent study 1.
Key Considerations
- CTA is particularly useful for actively bleeding patients, those who are hemodynamically unstable, or when rapid intervention is needed, with a sensitivity of 85% and specificity of 92% for detecting active GIB 1.
- Nuclear medicine (NM) GIB scans are more sensitive for detecting slow bleeding and can detect intermittent bleeding over longer monitoring periods, but are generally preferred for stable patients with intermittent or slower bleeding.
- The choice between CTA and NM GIB scans should consider the patient's clinical stability, suspected bleeding rate, and whether immediate intervention is required.
Advantages of CTA
- Faster results (minutes vs hours) compared to NM GIB scans
- Better anatomical localization
- Ability to detect bleeding rates of approximately 0.3-0.5 mL/min
- Helps identify vascular abnormalities that might be causing the bleeding
Limitations of CTA
- May not detect slow or intermittent bleeding if not actively occurring during the examination
- Does not allow intervention, requiring additional procedures if needed
Clinical Decision Making
- For unstable patients with active, rapid bleeding, CTA is the preferred initial imaging modality due to its rapid results and ability to guide intervention 1.
- For stable patients with intermittent or slower bleeding, NM GIB scans may be considered as an alternative, particularly if CTA is negative or unavailable 1.
From the Research
Comparison of CTA and Endoscopy for GI Bleeding
- CTA has been shown to have high sensitivity and specificity for diagnosis and treatment of GI bleeds, especially in differentiating arterial from venous bleeding 2.
- However, a study found that CTA has very poor sensitivity for identification of a GI bleeding source or lesion, suggesting that CTA should not be used as an initial diagnostic test 3.
- The European Society of Gastrointestinal Endoscopy (ESGE) recommends that patients with hemodynamic instability and suspected ongoing bleeding undergo computed tomography angiography before endoscopic or radiologic treatment to locate the site of bleeding 4.
Diagnostic Utility of CTA
- A study examined the diagnostic utility of CT angiography compared with endoscopy in patients with acute GI hemorrhage, and found that CTA had a sensitivity of 20% for the detection of a source of GI bleeding 3.
- Another study found that 64-row CTA detected active extravasation of contrast material in 57 patients with acute lower GI bleeding, resulting in an accuracy of 90.5% in the detection of acute GI bleeding 5.
Treatment Planning
- CTA can be used to determine whether the lower GI bleeding is suitable for endovascular treatment, surgical resection, or conservative treatment 5.
- A study found that treatment planning was correctly established on the basis of 64-row CTA with an accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 98.4%, 93.3%, 100%, 100%, and 97.5%, respectively 5.
Limitations of CTA
- CTA is not recommended as an initial diagnostic test due to its poor sensitivity for identification of a GI bleeding source or lesion 3.
- The ESGE recommends that colonoscopy should be performed sometime during the hospital stay of patients with major acute lower gastrointestinal bleeding, as there is no high quality evidence that early colonoscopy influences patient outcomes 4.