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

Ulcerative colitis (UC) is an idiopathic, non-specific inflammatory disorder involving primarily the mucosa and submucosa of the colon, especially the rectum. It usually produces a bloody diarrhea and various degrees of systemic involvement. These definitions of idiopathic proctocolitis were established by Council for International Organization of Medical Science (CIOMS) in 1973. In Japan, the first criteria for diagnosis of UC were established by the Research Committee of UC (the Japanese Ministry of Health and Welfare) in 1974, based on the definitions by CIOMS. Since then, some minor revisions have been made. The newest criteria for diagnosis of UC were published in 1998. The diagnosis of UC is made on the basis of a combination of clinical, endoscopic, radiologic, and histologic findings.