This is a screening test for cancer, to find the cause of diarrhea, abdominal pain, constipation, or to diagnose or monitor conditions such as ulcerative colitis or Crohn’s disease.
The doctor uses a flexible tube into the rectum and slowly guides it into the lower colon. As the doctor withdraws the tube, he or she looks through it, carefully examining the rectum and colon.
If the doctor finds anything unusual, he or she will remove a small sample of tissue using instruments inserted through the scope. The tissue sample is sent to a laboratory for examination under a microscope.