Radiology: CTA emerges as first-line exam for acute lower intestinal bleeding
CT angiography (CTA) represents a feasible and accurate diagnostic exam for patients who present to the emergency department with acute lower intestinal bleeding, according to a study published in the January issue of Radiology. CT revealed the presence and location of active or recent hemorrhage and often showed the potential cause in many patients.

Acute gastrointestinal bleeding presents a diagnostic and therapeutic challenge. Its location ranges from the esophagus to the rectum and severity varies, making rapid identification a priority. Current options include colonoscopy, scintigraphy and angiography, but these and other lesser used tests are constrained by multiple challenges.

Colonoscopy requires bowel prep, which could delay diagnosis or result in an incomplete study. Scintigraphy is not readily accessible in all emergency settings. Meanwhile, invasive angiography is reserved for severe, life-threatening cases.

Previous studies had suggested that CTA could accurately identify active bleeding or acutely hemorrhagic lesions, but were limited by small size or retrospective design.

Milagros Marti, MD, from the department of radiology at La Paz University Hospital in Madrid, Spain, and colleagues devised a prospective study to assess the diagnostic performance of CTA as the initial examination for patients presenting to the emergency department with acute lower intestinal bleeding.

The study population comprised 27 men and 20 women who presented to the emergency department from August 2008 to May 2010 with acute lower intestinal bleeding. Patients underwent CTA and data were reviewed prospectively by emergency radiologists.

CTA depicted active extravasation in 14 patients and intraluminal hyperattenuating material in six patients. In the remaining 27 patients, the study showed no evidence of active extravasation or hyperattenuating material.

The researchers calculated that CTA delivered 98 percent accuracy in establishing the presence or absence of acute or recent bleeding. Its diagnostic performance was a sensitivity of 100 percent, negative predicative value of 100 percent, specificity of 96 percent and positive predictive value of 95 percent.

“The inclusion of CT angiography in the diagnostic algorithm of acute lower intestinal bleeding helps identify patients with active bleeding and accurately determine the site of bleeding,” wrote Marti et al. The researchers noted that the diagnostic information could help physicians select the most appropriate method of intervention and enable targeted endovascular embolization, which reduces the number of angiographic series and saves time, radiation dose and contrast material.

Given the advantages of CT, coupled with the limits of colonoscopy and scintigraphy, Marti and colleagues proposed that CTA should be employed as the first diagnostic step in the evaluation of patients presenting with acute lower intestinal bleeding.