Before each procedure, the colonoscope is sterilized, which virtually eliminates the risk of infection. Some patients may feel some abdominal cramping or pressure when the physician pumps air into the colon to inflate it for better viewing.

Patients may have some blood in their first bowel movement after the procedure. This is normal. However, continued blood in the stool, abdominal pain or a fever of 100 degrees Fahrenheit (38 degrees Celsius) may indicate perforation of the colon or rectal wall. Although this is rare, it may require surgical repair to prevent significant bleeding. The risk of such perforation is higher in patients who have had a polyp removed during the colonoscopy.

In some cases, removal of a polyp or tissue sample for biopsy can cause heavy bleeding (hemorrhage) that may require a blood transfusion.

There is also the risk that some abnormalities may go undetected in a coloscopy. This may be affected by poor bowel preparation before the procedure, the skill of the physician in using the colonoscope and the patient’s anatomy.

Some research suggests that the risks of colonoscopies outweigh the potential benefits in individuals age 80 and older. All patients should address any concerns they may have about colonoscopies with their physician.