Colon Colon Colon: Ulcerative Colitis (Transition Zone) By Dr. Paul M. Choi Colon 29 September 2011 Hits: 2728 Share: Facebook Twitter Google+ A transition zone in the sigmoid colon, where acute colitis is juxtaposed next to the normal proximal colon in this 65 years old male with a year history of left-sided ulcerative colitis. Prev Next