All are impoant in the definition of ulcerative colitis, EXCEPT:

Definition of ulcerative colitis: Ulcerative colitis (UC) is a chronic inflammatory condition causing continuous mucosal inflammation of the colon without granulomas on biopsy, affecting the rectum and a variable extent of the colon in continuity, characterised by relapsing and remitting course. IBD unclassified (IBDU): cases where a definitive distinction between UC, Crohn's disease, or other cause of colitis cannot be made after the history, endoscopic appearances, histopathology of multiple mucosal biopsies and appropriate radiology have been taken into account. Indeterminate colitis is a term reserved for pathologists to describe a colectomy specimen which has overlapping features of ulcerative colitis and Crohn's disease. Ref: Journal of Crohn's and Colitis (2012) 6, 965-990.