The Simple Clinical Colitis Activity Index (SCCAI) describes how active ulcerative colitis is, using only what you report: bowel movements during the day and at night, urgency, blood in your stools, how you feel, and problems outside the gut such as joint pain. It was published in 1998 and scores from 0 to 20.
It needs no blood test, colonoscopy or examination, so you can fill it in yourself before an appointment. Studies usually count a score of 2 or under as remission.