Image of 83-year-old woman with acute rectal bleeding and hypotension. Source: Radiology

CT angiography (CTA) can accurately depict the presence and location of an active or recent hemorrhage in ED patients presenting with acute lower intestinal bleeding, and it should be considered as the preferred first step in diagnostic evaluation in such patients, according to a study published online Nov. 14 in Radiology.

Jorge A. Soto, MD, of the department of radiology at Boston Medical Center, and colleagues wanted to determine the diagnostic performance of CT angiography, primarily because the current preferred diagnostic procedures for gastrointestinal hemorrhages either have preparation challenges that limit use in an ED setting, such as colonoscopy, or can’t localize the precise source of bleeding, as is the case with scintigraphy.

The researchers performed a prospective study of 47 patients, mean age of 68 years, with acute lower gastrointestinal tract bleeding who were referred to undergo emergency colonoscopy. All patients underwent CT angiography shortly after arrival to the ED. Findings of ongoing or recent hemorrhages were compared with the standard of reference, which was the colonoscopy or, in some cases, conventional angiography and surgical findings.

CT angiography showed active bleeding in 14 patients and evidence of recent hemorrhage in six patients. Positive predictive value and negative predictive value of CT angiography in showing ongoing or recent hemorrhages was 95 and 100 percent, respectively. The findings of CT angiography were consistent with the standard of reference in 44 out of 47 patients.

“Rather than restricting it to cases where colonoscopy fails initially, in the majority of cases, we propose CT angiography as the first step in diagnostic evaluation of patients with substantial bleeding for confirmation of active or recent hemorrhage and correct identification of the site and cause of bleeding,” wrote the authors. “In this setting, despite some limitations, findings of our study confirm the high diagnostic performance of CT angiography, allowing us to propose CT angiography as a good alternative for the initial emergent evaluation of patients with acute lower intestinal bleeding.”

The principal limitation identified by the authors was the small patient group, which was limited by the requirement that patients must have been referred for colonoscopy, not simply present with a complaint of gastrointestinal hemorrhage. For this reason, the study did not have a true control group.

Nonetheless, the researchers recommended CT angiography due to the fact that it’s noninvasive, rapid, reproducible and widely available. It can also be performed without the need for colonic preparation.