(popping in from UC)
UC can spread...there are quite a few people over on the UC forum who have had it happen. For example, a person who was diagnosed with left-sided colitis now has pancolitis (whole colon affected). It won't, howerver, ever spread beyond the colon, so that's why we can have a colectomy and be cured. However, even if a person only has left-sided colitis, they'll still remove the entire colon, as there's no guarantee it won't affect the remaining part of the colon.
I was diagnosed with pancoltis, so mine won't spread. ;)
Status: Remission since May 2009!
Symptoms began in November 2008, ~4 weeks after giving birth to my son
Diagnosed with pancolitis on 1/30/09
Meds: Apriso (4 0.375g pills ONCE!! daily), mesalamine enema twice weekly, Natural Factors Ultimate probiotic 12/12 Formula, OrthoNovum, multivitamin. Used prednisone (starting dose 40 mg) to get into remission.
Thread with links to UC resources and information: