While I have not had the surgery, I have been dealing with constipation since I was a baby, and have recently become a member of this site. The doctors I am going to now have the sitzmark/breath test/manometry...etc. tests planned for me in January, but based on all I have been through and all the medications/diets/lifestyle changes I've tried, my new GI doctor says that if the tests go as she think they will, they will show that my colon is just "slow as heck". She says she thinks it is colonic inertia. However, I won't know anything for sure until after the tests.
I asked about long-term options if I DO have CI, and she said that if everything else keeps failing, and there are no other issues other than the slow large intestine, then we could discuss removing it. She said the same thing, that if the actual colon muscles are the problem, no amount of exercise, special diets, or whatever, will really work.
I can't give advice on the actual procedure but I did want to tell you that the surgery has been mentioned as a possibility for me also, and I do not have chron's or UC, or anything like that, so I know they do also do the procedure on people with severe constipation.
I am curious, how did your sitzmark test go? And how did yours work? I know many people have had the kind where they take one capsule and go back 5 days later for an x-ray. I have to take 5 capsules, one per day, and go on the 6th day for an x-ray.
I am 24, close to your age. I am hoping they can figure this out and fix it soon because I've lost most of my 20's to this and don't want to lose more time.