Dwarkadelhi Blog » Gastrointestinal Procedures that can Save Lives : Colonoscopy is probably the most recognized gastrointestinal procedure. The large intestine and bowel are examined here. If there is blood in the stool, abdominal pain, diarrhea a change in bowel habits, or any other abnormality, a colonoscopy is recommended. You are recommended to have your first colonoscopy when you turn 50, then one every 10 years. This procedure is both diagnostic and therapeutic. Routine colonoscopies can reduce your risk and even prevent colon cancer.