Patients with newly diagnosed ulcerative colitis (hereafter referred to as UC) are usually between the ages of 15-35 and may have been suffering from this chronic disease for years prior to diagnosis. For these patients, it is important to be able to understand, with brief information, what will happen in the years or even decades to come. This article provides a brief overview of the clinical presentation, course, and long-term prognosis of UC. The clinical course of UC is usually considered to have four patterns: the first is the classic relapsing-remitting pattern, which fits about 90% of patients; the second is acute fulminant or refractory, which means that the disease is very severe at the beginning of the disease and therefore may require emergency surgery or surgery within 1 year of diagnosis in about 10% of patients; the third pattern may have only one typical episode in a lifetime The fourth pattern has an active course throughout the patient’s life. The latter two clinical courses are relatively uncommon. Prognostic factors The main prognostic factors of UC include (1) the extent of colonic inflammation and (2) the severity of the disease. Foreign clinical data show that in 40% of newly diagnosed patients, the lesion is confined to the rectum, 30-40% have a left hemicolectomy, and 20-30% have a total colon lesion, where patients with a total colon lesion tend to have a poor prognosis with a higher rate of surgery and risk of colon cancer. The severity of the disease is determined by a combination of clinical symptoms (e.g., frequency of bowel movements, bloody stools, fever, tachycardia) and laboratory indicators (e.g., C-reactive protein, hemoglobin, etc.). As an indicator of disease severity and extent of lesions, the need for glucocorticoids at the time of diagnosis is a predictor of poor disease prognosis. Data from a population-based study showed that 1/3 of patients required glucocorticoid therapy at diagnosis, and approximately half of these patients subsequently required long-term hormonal or surgical treatment. Protective factors for UC, on the other hand, include smoking and appendectomy. A number of studies have found that patients with UC who do not smoke or quit smoking tend to have more severe disease. Not only does surgical appendectomy have the potential to prevent UC, but patients with UC who have a history of appendectomy usually have less severe disease. The total colectomy rate for UC patients is about 10% in the first year, 4% in the second year, and 1% per year thereafter. This means that if a patient does not require total colectomy in the first few years of diagnosis, the probability that the patient will require colectomy for active lesions in subsequent years is very low. The cumulative rate of surgery within 5 years of diagnosis is 35% for patients with total colon by lesion site, compared to 9% for patients with rectal lesions only. Recent reports suggest that the current rate of colonic resection for UC is lower than previously reported. Studies have shown that treatment with cyclosporine A for refractory or fulminant UC reduces the short-term surgical rate (i.e., reduces the rate of emergency surgery), but long-term follow-up has found that half of these patients eventually require surgical treatment. The use of infliximab instead of cyclosporine A in the treatment of refractory UC is currently being used in many centers to spare patients from surgery, but adequate data on its long-term efficacy are lacking. Survival Foreign epidemiological data show an increased mortality rate in the first years of UC diagnosis, which is associated with severe or fulminant UC and complications after total colectomy. Overall long-term survival of UC patients is not significantly different compared to the general population, but mortality is mildly increased due to hepatobiliary disease and colon cancer. Colon cancer The risk of colon cancer in patients with UC is 8-10 years after diagnosis, therefore, it is recommended that regular follow-up colonoscopic surveillance for atypical hyperplasia should be performed from this point onwards. Due to observational bias and methodological flaws, early studies significantly overestimated the risk of developing colon cancer in UC. Recent studies have shown that the risk of developing colon cancer in UC patients is 2% at 10 years, increasing annually to 8% at 20 years and 18% at 30 years. Thus, the risk of colon cancer in UC patients is about 2-3 times higher than that of the general population. Colon cancer is usually more likely to occur in patients who are diagnosed at a young age (less than 15 years) and have a full colon. Patients with UC who also have primary sclerosing cholangitis and a family history of colon cancer are at increased risk of developing colon cancer.