Q2. Correct answer: E
Rationale:
Radiographic evaluation is commonly employed in the diagnosis and management of patients with lower GI bleeding. CT scans, tagged red blood cell scintigraphy, and angiography all have roles in the care of these patients. Though tagged red blood cell scintigraphy is the most sensitive modality at detecting active bleeding, requiring rates from 0.05-0.1 cc/min, it is relatively poor at localizing the bleeding, accurately predicting the location in only 60%-70% of cases. CT scans have the advantage of being quickly performed and are widely available. If extravasation is seen, its location is also accurately determined. It is not as sensitive as red blood cell scintigraphy, however, and requires bleeding rates of 0.3-0.5 cc/min to be positive. Angiography has the advantage of being both diagnostic and potentially therapeutic. It is best performed in sicker patients with hypotension and high transfusion demands as it is higher yield in these situations. Angiography is the least sensitive of these modalities, requiring bleeding rates between 0.5 and 1 cc/min to be positive.
Reference:
1. Strate LL, Naumann CR. The role of colonoscopy and radiological procedures in the management of acute lower intestinal bleeding. Clin Gastroenterol Hepatol. 2010 Apr;8(4):333-43.
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