From the Guidelines
For a patient with massive lower GI bleeding and no blood in the nasogastric tube (NGT), the recommended approach is to proceed with CT angiography (CTA) as the initial diagnostic step, given the patient's hemodynamic instability, as suggested by the most recent and highest quality study 1. This approach is based on the guidelines from the American College of Radiology, which recommend CTA as the initial diagnostic step for hemodynamically unstable patients with lower GI bleeding 1. The absence of blood in the NGT suggests the bleeding source is likely distal to the ligament of Treitz, making lower GI bleeding more probable than upper GI bleeding. CTA allows for rapid localization of the bleeding site and can detect active bleeding rates as low as 0.3 mL/min, making it an ideal initial diagnostic step for hemodynamically unstable patients. If CTA identifies a bleeding source requiring embolization, conventional angiography would be considered as the next step. Alternatively, if CTA does not identify a bleeding source, colonoscopy may be considered as a subsequent diagnostic step, as it allows for direct visualization of the colon and terminal ileum, potentially identifying the bleeding source and enabling therapeutic intervention such as cauterization, clipping, or injection therapy 1. Key considerations in the management of lower GI bleeding include:
- Hemodynamic stability: CTA is recommended as the initial diagnostic step for hemodynamically unstable patients 1
- Localization of the bleeding site: CTA and conventional angiography are useful for localizing the bleeding site 1
- Therapeutic intervention: Colonoscopy and conventional angiography allow for therapeutic intervention, such as cauterization, clipping, or injection therapy, and embolization, respectively 1
From the Research
Diagnostic Approach for Lower GI Bleeding
- The patient was referred from the burn unit to the ER for massive lower GI bleeding with no blood in the NGT, indicating the bleeding is likely originating from the lower gastrointestinal tract.
- According to the study by 2, the European Society of Gastrointestinal Endoscopy (ESGE) recommends that patients with major acute lower gastrointestinal bleeding undergo computed tomography angiography before endoscopic or radiologic treatment to locate the site of bleeding.
- However, the study by 3 found that CT angiography has poor sensitivity for identifying a GI bleeding source or lesion, suggesting it should not be used as an initial diagnostic test.
- In contrast, the study by 4 found that 64-row computed tomographic angiography is safe and effective in making decisions regarding treatment in patients with lower GI bleeding, with high accuracy, sensitivity, and specificity.
Recommended Diagnostic Steps
- The study by 5 suggests that computerized tomography (CT) can be used to identify the source of bleeding in patients with negative or failed endoscopy.
- Based on the available evidence, a possible diagnostic approach could be:
- Upper GIT endoscopy to rule out upper GI bleeding
- If negative, proceed with colonoscopy to investigate the lower GI tract
- If colonoscopy is negative, consider CT angiography to locate the site of bleeding, as recommended by 2
- However, the choice of diagnostic steps may depend on the specific clinical presentation and institutional protocols.
Role of CT Angiography
- CT angiography can be a useful tool in diagnosing and managing lower GI bleeding, as shown in the study by 4.
- The study by 6 provides a practical resource for radiologists interpreting GI bleeding CT studies, including guidelines for case interpretation and a CT reporting template.
- However, the study by 3 highlights the limitations of CT angiography in detecting GI bleeding sources or lesions, and it should be used in conjunction with other diagnostic modalities.