American Journal of Gastroenterology vol:92 issue:8 pages:1275-9
OBJECTIVES: It is generally believed that the mucosal inflammation in ulcerative colitis is characterized by a diffuse, continuous involvement starting from the rectum without "skip areas." It was the aim of this study to examine 20 patients with established "left-sided ulcerative colitis" prospectively by ileocolonoscopy with biopsies to determine the extent and the continuity of the mucosal inflammation and the incidence of skip lesions in ulcerative colitis. METHODS: Twenty patients with left-sided ulcerative colitis underwent a complete ileocolonoscopy with biopsies of the terminal ileum and all colonic segments. The patients remained in clinical follow-up for at least 8 yr after the initial examination. RESULTS: The upper margin of inflammation was sharply demarcated in 6 patients and gradual in 14. Segmental inflammation, separated from the distal inflamed segment by apparently uninvolved mucosa, was found in 15 patients (75%) and always included the area around the appendiceal orifice. The correlation between endoscopic abnormalities and histological changes was excellent. CONCLUSION: In so-called "left-sided" ulcerative colitis distal involvement may be accompanied by more proximal areas of inflammation, particularly in the periappendiceal area of the cecum.