Posted 3/27/2015 6:03 AM (GMT -6)
You can have a flare that involves less, or more, of the colon than what you've had in the past. For instance, I was diagnosed with pancolitis. I had a very mild flare about a year ago, and while I didn't have a scope to confirm, my GI and I both thought that it was highly likely just a small portion of my colon was affected, because my symptoms were so mild. I also know of people who were diagnosed with pancolitis, to have subsequent flares only involve the left side, etc.
Generally, though, with UC, the inflammation always starts at the rectum and moves up from there. It's quite rare for UC to be "patchy." So your example of UC only affecting the upper left quadrant would not often happen - it could show up that way on a scope if the patient had been using rectal meds, though, and the rectal meds healed the portion of the colon they can reach.