I think it means you have chronic inflamation through the sigmoid and left colon. The rectum itself looked good.
Unless there is also histology that describes cell changes consistent with idiopathic UC, this could still be infectious UC, or allergic reaction, or something other than the relapsing remitting autoimune kind.
Usually and detailed discussion of reports are done at followup visits, which can be weeks later, or even get lost if you primary had sent you to a gi for diagnosis - because then it is unclear who will follow you. I had to make several calls to find out I was getting a gi appointment, and then to get the nurse to have some prescript
ions sent in the meanwhile.
the language you see seems to be part of a standardized naming system called SNOMED. I had not hear of it before, but the phrase popped up in google.
www.snomedbrowser.com/Codes/Details/369445005systems.hscic.gov.uk/data/uktc/snomed