Hi Cai Shum,
A colonoscopy is one of the investigative tools we have to examine the colon, rectum and in some cases the terminal ileum. The alternatives are a computed tomography scan of the colon (also known as a CT Colonography) and a barium enema.
The key benefit of performing a colonoscopy is the ability to directly visualize the colonic lumen through a high definition lens and biopsy the lesion if necessary.
This cannot be done with the other imaging options. The common example is the poorer ability of scans to differentiate small polyps from stool remnants, as well the inability of scans to remove these polyps (polypectomy) should they be present.
This leads to an additional procedure with the additional inconvenience, cost, and effort attached with it.
