<prompt> Which of the following is MOST commonly affected in U.CCecumRectumSigmoid colonTerminal leum  <response>: Ans. is b i.e., Rectum The most common site of involvement in Ulcerative colitis is the rectum. Ulcerative colitis involvement is limited to the colon Ulcerative colitis typically stas in the rectum and may progress with continuous lesions no skip lesions in a retrograde manner to involve the entire colon Pancolitis. UC is a mucosal disease that usually involves the rectum and extends proximally to involve all or pa of the colon. About 40 to 50 of patients have disease limited to the rectum and rectosigmoid, 30 to 40 have disease extending beyond the sigmoid but not involving the whole colon, and 20 have a total colitis. Proximal spread occurs in continuity, without areas of uninvolved mucosa 