Are stool samples collected by a digital rectal exam (DRE) allowed to be used for the gFOBT and FIT tests? 

Stool specimens collected during a DRE can contain red blood cells (false positive) as a result of the collection method as opposed to a natural bowel movement. Guidelines from ICSI and the American Cancer Society discourage collection of stool specimens during DRE. The ICSI guideline states: While stool collection and gFOBT or FIT have sometimes been performed as part of a digital test in the office research has demonstrated that the sensitivity of in-office sample is so low that its use should be discouraged (Levin, 2008; Collins, 2005). According to the American Cancer Society Colorectal Cancer Early Detection Guide (2013): An FOBT or FIT done during a digital rectal exam in the doctor's office is not adequate for screening.