Colonoscopy (koh-luh-NAH-skuh-pee) lets the physician look inside your entire large intestine (another name for the colon), from the lowest part, the rectum, all the way up through the colon to the lower end of the small intestine, the terminal ileum.
Upper endoscopy enables the physician to look inside the esophagus, stomach, and duodenum (first part of the small intestine). Upper endoscopy is also called EGD, which stands for esophagogastroduodenoscopy (eh-SAH-fuh-goh-GAS-troh-doo-AH-duh-NAH-skuh-pee).
read more about upper endoscopy
Flexible sigmoidoscopy (SIG-moy-DAH-skuh-pee) enables the physician to look at the inside of the large intestine from the rectum through the last part of the colon, called the sigmoid or descending colon. Physicians may use the procedure to find the cause of diarrhea, abdominal pain, or constipation. They also use it to look for early signs of cancer in the descending colon and rectum and to monitor therapy in patients with inflammatory bowel disease including Crohn’s disease and ulcerative colitis.