Angiodysplasia of the colon is a common cause of lower gastrointestinal (GI) bleeding. It is estimated that these vascular lesions account for up to 50 percent of hemorrhage cases of obscure origin. Current methods of viewing these lesions include endoscopy and catheter angiography. Unfortunately, endoscopic imaging may fail to show these lesions in up to one third of cases. Angiography, while recognized as an alternative to colonoscopy, may not be readily available and is associated with significant complications in up to 9 percent of patients. Computed tomography (CT) has gained acceptance as a minimally invasive technique for imaging the vascular system. Helical CT and CT angiography (CTA) have been shown to be as useful as conventional angiography in the assessment of the abdominal aorta and its branches. The usefulness of CTA in the visualization of smaller vascular lesions has not been established. Junquera and associates performed a study of helical CT angiography in the diagnosis of colonic angiodysplasia.

Thirty consecutive patients with lower GI hemorrhage and clinical suspicion of bleeding from colonic angiodysplasia were evaluated for the study. Twenty-eight patients met the inclusion criteria and participated in the study. Patients initially underwent upper endoscopy, followed by colonoscopy. When both procedures were negative, all patients underwent visceral angiography. Afterward, all eligible patients underwent helical CT angiography. Notable results included CT angiographic images of diagnostic quality in 26 of the 28 patients. Eighteen of these 26 patients were found to have angiodysplasia. Helical CT angiography detected angiodysplasia in 14 of these 18 patients (sensitivity, 78 percent). No signs of angiodysplasia were detected in any of the eight patients negative for angiodysplasia by CTA.

While there are recognized limitations to this technique, including the inability to detect active bleeding, this small study shows that helical CT angiography may have a role in the diagnostic evaluation of patients with lower GI bleeding of unclear etiology.