What is the role of CTA in the evaluation of lower gastrointestinal (GI) bleeding?

Updated: Jul 26, 2019
  • Author: Burt Cagir, MD, FACS; Chief Editor: BS Anand, MD  more...
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Answer

Computed tomographic angiography (CTA) has emerged as a favorable alternative in the workup and management of acute lower gastrointestinal bleeding (LGIB), with improvement in imaging studies. CTA is a cost-effective, accurate, and rapid tool in the diagnosis of acute LGIB. [34] Studies report a pooled sensitivity of 85.2% to 89% and a specificity of 74% to 96.9%. [34, 35, 36]

Kim et al found that the diagnostic yield of CTA to identify a definite or potential bleeding focus was 61.3% (68 of 111 emergency department [ED] patients with overt GI bleeding). [36] The overall positive predictive value (PPV) was 98.5% (67 of 68), and the negative predictive value (NPV) was 72.1% (31 of 43). [36]

In retrospective, single center retrospective study (2012-2016) to evaluate the negative predictive power of CTA for identifying obscure acute GI bleeding in 20 patients who also underwent subsequent mesenteric angiography (MA), Shukla et al reported a high CTA NPV of 90% (18 of 20 patients had negative subsequent MAs). [37] The investigators suggested that CTA may be considered as a first-line diagnostic study in the evaluation of obscure GI bleeding. [37]


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