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Fecal Occult Blood Testing

Which Test?

Occult Bleeding From Colorectal Cancer

Slide 11

October 2011

Colorectal cancers do bleed…but bleeding is often intermittent and, at times, absent. In a study we conducted on 10 patients with colorectal cancer in whom fecal blood levels were quantified by HemoQuant and also tested by Hemoccult over a 2 week intensive collection period, this point is illustrated. Fecal blood levels commonly fell within the normal range of <2mL/day as shown in the blue shaded area, and Hemoccult was positive in only 3 patients. The positive patients were the green circles, the negative were the blue circles. In patients with hemorrhagic cancers, high fecal blood levels may be expected as shown here….but, in those with normal levels, small nonhemorrhagic tumors are more likely. An important take home point is that occult blood, however well measured, is an imperfect and inconsistent marker for colorectal neoplasia.

Occult Bleeding From Colorectal Cancer


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