Checking for "the occult" with a finger. A procedure of little value.

The performance of an occult blood test on normal-appearing feces obtained by rectal examination probably yields such high rates of false positive and false negative reactions that it is of little value in the detection of colorectal neoplasia. In acute gastrointestinal bleeding, it helps to know what the stool looks like; nevertheless, many physicians merely describe it as "heme positive" and neglect to record its gross appearance. Both of these practices should be discouraged.