The issue here is Crohn's is an inflamatory bowel disorder and IBS is NOT. IBS does not lead to Crohn's. They would also not remove someones colon with IBS.
They have done some research on using Naltrexone in IBS with mixed resuilts I believe, if I remeber correctly.
This sounds like an inflammatory bowel problem and heance why the doctor might want to remove part of the colon if its in bad shape.
I am not a doctor. All information I present is for educational purposes only and should not be subsituted for the advise of a qualified health care provider.
Please make sure you have your symptoms diagnosed by a medical practitioner or a doctor.