I had a medical misadventure with IBD, ulcerative colitis to be exact.
One of the diagnositic procedures is a colonoscopy. the colonoscopy itself was no big deal, you're out like a like with the IV meds. The prep is less pleasant than many other things in life. You get some super gross liquid (either 1 gallon of GoLytley or 2 ounces of phospho soda) and you drink it. The you strap yourself to the toilet for a couple hours... jet propelled output! (sorry, gross but true). There is a pill version prep that is relatively new (not available when I had my test). You take 20 pills and quite a lot of water. I'd sure pick that over the other... if there was a choice.
As I have, indeed, conquered the UC by having my colon removed, I shall never have another colonoscopy.
Having sat in the office with many who had other issues, I'd say that if the doctor has ordered one, then it's necessary. It can find and detect problems LONG before they are cancerous, or prevent issues with diverticulitis. Both of these issues can, and often do, end with the same colon removal surgery that I had if you DO NOT have the test run.
Had I had the test done earlier, I might still have an intact digestive tract.
Please consider seriously getting it done. Better safe than sorry.