This procedure takes 30 to 60 minutes. It can be done as an outpatient procedure, but is usually done in the hospital. With the patient lying on his or her side and knees flexed, a colonoscope is passed through the intestine. Air may be injected to expand the folds of the colon, enabling the doctor to see the entire surface area. When the tube has reached the entire length of the colon, it is slowly withdrawn as the doctor examines the lining for any lesions or polyps.
Special attachments allow the removal of some small polyps or the collection of a biopsy sample.
There is very little risk of bowel perforation, but the patient should report any bleeding, dark stool, or abdominal pain. Many patients feel embarrassment and discomfort during this procedure, especially when air is injected and expelled.