Ulcerative colitis is categorized according to location:
Proctitis involves only the rectum
Proctosigmoiditis affects the rectum and sigmoid colon
Left-sided colitis encompasses the entire left side of the large intestine
Pancolitis inflames the entire colon
Review Date: 10/8/2012 Reviewed By: George F. Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program, San Diego, California. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, and Stephanie Slon.