MDCT and CT angiography evaluation of rectal bleeding: the role of volume visualization.

OBJECTIVE: This article reviews several different causes of rectal bleeding and the role of MDCT in diagnosis.

CONCLUSION: Although colonoscopy remains the first-line modality for the diagnosis of lower gastrointestinal tract bleeding, colonoscopy may not be possible for unstable patients, and moreover, even for patients who undergo colonoscopy, the examination may still fail to diagnose a cause for bleeding. MDCT with CT angiography and 3D mapping now offers a valuable option for diagnosis, not only for patients whose colonoscopy findings were negative, but also as a first-line screening modality for patients with active bleeding and hemodynamic instability. This article reviews the valuable role of MDCT in the diagnosis of multiple different causes of rectal bleeding, including rectal vascular malformations, rectal varices, ischemic colitis, stercoral colitis, inflammatory bowel disease, radiation proctopathy, infectious colitis, and rectal cancer.