It is not on the tissue or on the stool itself but rather part of the stool. The procedure is done to look for a site of bleeding in the left side of the large intestine or as a screening test for colon cancer in persons over the age of 50. As a general rule it is a procedure that takes less than 15 minutes. It is usually done without sedation. Patients can sometimes experience gas pains or discomfort during the procedure because air is pumped into the large intestine to enhance visualization.
Some patients have twists or turns in the sigmoid colon which can be a source of discomfort.
Nevertheless, most patients tolerate the procedure well without complications. This may necessitate surgical repair, but again, this is very rare with a flexible sigmoidoscopy. However, a flexible sigmoidoscopy can help to exclude causes of bleeding which occur at a level above the anal canal. If an abnormality is found during the flexible sigmoidoscopy it may be necessary to perform biopsies of the large intestine. This involves taking small samples of tissue to be sent to the laboratory for interpretation by a pathologist.