Gastrointestinal ImagingFree Access

Invited Commentary: GI Bleeding at CT Angiography and CT Enterography—The Hunt for the Elusive Source of Bleeding

Published Online:

See also the article by Guglielmo et al in this issue.

As most radiologists would likely attest, especially those working at emergency referral or tertiary care centers, the treatment of gastrointestinal (GI) bleeding, whether the patient is presenting for the first time or with repeated episodes, is challenging. The struggle is due to the peculiar aspects of this condition, including the acute urgency of treating potentially life-threatening bleeding, the frequency of GI bleeding in older patients with multiple comorbidities, the need for a multidisciplinary approach to treatment (ie, involvement of practitioners from the emergency medicine, gastroenterology, surgery, and diagnostic and interventional radiology disciplines), and the lack of familiarity among diagnostic radiologists with the imaging findings of GI bleeding. Adding to the diagnostic challenge are the lack of consensus on an optimal imaging protocol and the need for multiphasic imaging (ie, the high number of images acquired), which have a combined effect on the accuracy and diagnostic yield of the interpretation.

Mastering knowledge of the many potential causes of bleeding (ie, vascular lesions such as angioectasia, Dieulafoy lesions, and arteriovenous malformations; ulcers; and ischemic, drug-induced, inflammatory, infectious, or malignant causes) is also particularly challenging. Providing an atlas of imaging findings for specific diseases as a quick resource is an excellent and well-established way to ensure dissemination of the information and terminology to fill this knowledge gap (1,2).

In this issue of RadioGraphics, the Society of Abdominal Radiology GI Bleeding Disease–Focused Panel presents the first comprehensive atlas for GI bleeding (3), which they compiled as experts in the field. Most causes of bleeding are included, with imaging examples, comments on optimizing imaging techniques, and a suggested template for reporting (3). The atlas also includes a glossary with definitions of appropriate reporting terms to ensure proper communication of results to the referring providers. Without the use of a common lexicon, members of the multidisciplinary team risk creating confusion and misunderstanding, which can have a serious and detrimental effect on patient care. This atlas is an invaluable resource for practicing radiologists that will be used for years to come to increase radiologists’ confidence in interpretation, decrease confusion about the causes of GI bleeding, and consequently improve patient care.

Although this type of resource is important for filling this educational gap, radiologists must also consider and take into account several scenarios that affect the selection and timing of diagnostic and/or therapeutic interventions. In which cases we should start with endoscopic evaluation, and in which should we resort to earlier cross-sectional imaging? Which modality among endoscopy, CT angiography, digital subtraction angiography, and nuclear medicine should we use to localize and diagnose the cause of the bleeding, and in which order should imaging studies be performed? What is the effect of bleeding rate on the sensitivity of the examination used? When should we optimally image, and how often should we repeat imaging if the initial evaluation fails to localize the bleeding site? All of these different challenges can be at least partly overcome by close collaboration with and open communication among practitioners from all involved disciplines.

Also important is to establish a clear understanding of an institutional algorithm based on the published recommendations and consensus statements from different societies such as the American College of Gastroenterology, the American Society for Gastrointestinal Endoscopy, and the British Society of Gastroenterology, to name a few (46). The recommendations in these published algorithms vary depending on the acuteness of the bleeding, whether it is the patient’s first instance of bleeding or is recurrent bleeding, the site of suspected bleeding (eg, upper GI, small bowel, or lower GI), the potential cause, and whether the patient is in stable or unstable condition. Of course, the institutional algorithm used ultimately depends on the local expertise and availability of endoscopists, interventional radiologists, and surgeons for optimal patient treatment. All of these steps help to ensure proper implementation of the chain of events after patient presentation to avoid unnecessary delays in obtaining diagnostic test results, when indicated, and to localize the bleeding source and identify the cause, which affects decisions on management of bleeding and patient treatment.

The author has disclosed no relevant relationships.


  • 1. MacMahon H, Naidich DP, Goo JM, et al. Guidelines for Management of Incidental Pulmonary Nodules Detected on CT Images: From the Fleischner Society 2017. Radiology 2017;284(1):228–243.
  • 2. Guglielmo FF, Anupindi SA, Fletcher JG, et al. Small Bowel Crohn Disease at CT and MR Enterography: Imaging Atlas and Glossary of Terms. RadioGraphics 2020;40(2):354–375.
  • 3. Guglielmo FF, Wells ML, Bruining DH, et al. Gastrointestinal bleeding at CT angiography and CT enterography: imaging atlas and glossary of terms. RadioGraphics 2021;41(6):1632–1656.
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Article History

Received: June 10 2021
Accepted: June 15 2021
Published online: Oct 01 2021
Published in print: Oct 2021