Ulcerative colitis is an inflammatory bowel disease (IBD) that causes long-lasting inflammation and ulcers (sores) in your digestive tract. Ulcerative colitis affects the innermost lining of your large intestine (colon) and rectum. Symptoms usually develop over time, rather than suddenly. Ulcerative colitis can be debilitating and sometimes can lead to life-threatening complications.
Doctors often classify ulcerative colitis according to its location. Types of ulcerative colitis include: ulcerative proctitis, proctosigmoiditis, left-sided colitis, pancolitis, and acute severe ulcerative colitis.
Ulcerative Colitis, Mayo Clinic (Mar. 8, 2018), https://www.mayoclinic.org/diseases-conditions/ulcerative-colitis/symptoms-causes/syc-20353326