Ulcerative colitis can be characterized by both severity — how badly inflamed the colon is at the site of disease activity — and what areas of the colon it affects. These two factors in combination can explain a lot about why you experience certain symptoms.
What Tests Will I Need to Evaluate the Severity of My UC?
Ulcerative colitis can be roughly grouped as mild, moderate, or severe, according to Daniel Stein, MD, associate professor and director of the inflammatory bowel disease program at Froedtert and the Medical College of Wisconsin in Milwaukee. Your doctor can determine the severity of the disease based on symptoms, lab tests, and the results of a colonoscopy. These tests also help rule out other medical conditions that mimic the symptoms of UC. According to Dr. Stein, the main symptoms that doctors look at when rating UC severity are the number of bowel movements per day, amount of blood in the stool, weight loss, and reports of a poor appetite. Important lab tests for determining the severity of a person’s UC can identify nutritional markers, like iron and protein stores, which indicate more severe disease when they’re lower. Doctors can also check for markers of inflammation in the blood, such as C-reactive protein. A similar but less intrusive procedure is a flexible sigmoidoscopy. This procedure uses a flexible tube with a light to view just the lower portion of the colon. A definitive diagnosis of ulcerative colitis is generally made using endoscopy — that is, a colonoscopy or a sigmoidoscopy. In addition to reported symptoms, lab tests, and endoscopy results, some people receive CT (computerized tomography) scans to assess inflammation in the colon, although the role of these scans is currently more limited in UC than in Crohn’s disease. If the UC is in remission, the severity of the disease, which is determined using a rating system based on colonoscopy results, can help predict how likely it is to relapse within five years, according to a study published in August 2021 in the International Journal of Colorectal Disease.
What Are the Types of Ulcerative Colitis?
Another way to categorize ulcerative colitis is by identifying what areas of the colon it affects, as seen in a colonoscopy. According to Stein, UC always affects the rectum, the lowest section of the colon. But it may also affect higher parts of the colon. There are four main types of UC based on how much of the rectum and the colon are affected: Ulcerative Proctitis This form of UC usually affects less than six inches of the rectum and is found in about 30 percent of people at the time of diagnosis. Because of its limited extent, it tends to be associated with less severe disease and fewer complications. Proctosigmoiditis This form of UC affects the rectum as well as the sigmoid colon, located just above the rectum. Proctosigmoiditis tends to be more severe than ulcerative proctitis, frequently causing symptoms such as bloody diarrhea, cramps, and tenesmus (constantly feeling the need to pass stool). Left-Sided Colitis Inflammation extends even farther up the colon in this form of UC, to a point where it bends near the spleen. It tends to be even more severe, with common symptoms including diarrhea, bleeding, loss of appetite, weight loss, and severe abdominal pain on the left side. Pan-Ulcerative Colitis This form of UC involves inflammation throughout the entire colon and tends to be the most severe variation with the greatest risk of complications that require surgery. Symptoms often include severe diarrhea, bleeding, cramps, abdominal pain, and weight loss. Ulcerative colitis can become more extensive, affecting a larger area of the colon over time. In a long-term study published in July 2020 in Gut, researchers analyzed 30 years of medical records and found that overall, 28.7 percent of people with proctitis or left-sided UC saw their disease worsen over time.
Long-Term Impacts of Your UC Type
While Stein notes that greater involvement of the colon usually means more severe UC, that doesn’t always hold true: “You could have somebody with very limited disease, just in the rectum, but very severe disease, with deep ulceration and marked swelling and bleeding,” he says. In such cases, though, the person is still far less likely to experience problems like malnutrition and weight loss than someone with more extensive UC, Stein says. On the other hand, “You can also see somebody whose entire colon is involved but with very mild disease,” says Stein. “And they may only have three or four bowel movements a day and not see any blood in their stool.” In general, Stein says, the level of inflammation in the rectum, rather than higher areas of the colon, accounts for the greatest share of UC symptoms that people report. “If the rectum is relatively healthy compared with the rest of the colon,” he says, “people can often control their symptoms a little bit better.” How much of your colon is affected probably won’t have an enormous impact on how your doctor recommends treating the condition, says Stein. “The anatomic features do have a factor in it,” he says, adding that they are just one element among several. “The whole clinical picture, from symptoms to laboratory abnormalities to how inflamed the colon looks, will guide us to which clinical therapies we choose.” Regardless of the extent or severity of the UC, Stein emphasizes the importance of receiving proper treatment. “Many physicians, including myself, feel that ulcerative colitis, if left untreated, will progress over time,” he says. That includes many people with milder UC, who often let their condition “smolder for a while before they actually come and see a doctor,” Stein says. Additional reporting by Jordan M. Davidson.
