[The concept, criteria for diagnosis, and disease classification of ulcerative colitis]

The concept of ulcerative colitis(UC) in Japan has been defined based on the definition of idiopathic proctocolitis by CIOMS. UC is an idiopathic, non-specific inflammatory disorder involving primarily the mucosa and submucosa of the colon, especially the rectum, often with mucosal erosions and ulcers. Criteria for diagnosis of UC consist of the following three conditions; one is continuous or repeated findings of hematochezia or mucous and bloody stools, second is colonoscopic and/or X ray findings characteristic of UC, and third is histopathological findings consistent with UC pathology. Disease classifications of UC are divided in many clinical aspects such as disease extents, disease activity, disease severity, clinical courses, endoscopic grades, and disease conditions for obtaining financial supports by Japanese government.