Endoscopy is a procedure that uses an endoscope (a thin, flexible tube with a light and a lens on the end) to look into the esophagus, stomach, duodenum, small intestine, colon, or rectum. Two types of endoscopy procedures are commonly used to diagnose or treat constipation: colonoscopy and sigmoidoscopy.
Colonoscopy is an examination whereby an endoscope is inserted through the anus into the intestine. An image of the entire large bowel, or colon, is relayed through the instrument onto a video screen.
Sigmoidoscopy is a similar test, but only the lower portion, the left side, of the colon is seen. This includes the rectum and sigmoid colon.
Both tests use instruments which are equipped with ports or passages through which air and water can be passed into the colon, and excess fluids may be sucked back. Biopsy forceps, polyp snares, and other instruments may be passed through these ports as well.
The colonoscopy should be done in a licensed facility. The staff is specially trained for this test and, though rarely needed, the unit will be equipped with suitable emergency equipment. Such facilities require a hospital setting, or a freestanding clinic facility, usually staffed by gastroenterologists. Sigmoidoscopy may be done in a doctor's office.