This site is intended for US Healthcare Professionals only.
This site is intended for US Healthcare Professionals only.


Ulcerative colitis (UC) is a chronic, idiopathic inflammatory disease of the colonic mucosa that typically starts in the rectum and spreads proximally through part of or the entire colon in a continuous pattern.1 UC has an increasing incidence worldwide, with nearly one million individuals each in the US and Europe affected by this condition and many more throughout the world.2


The etiology of UC is unknown, but a number of factors are thought to contribute to the disease including an impaired mucosal barrier, dysbiosis, and dysregulated immune responses. UC may result from a dysregulated immune response to commensal enteric microflora in genetically susceptible individuals. In patients with UC, there is an increased infiltration of innate immune cells (neutrophils, macrophages, dendritic cells, and natural killer T cells) and adaptive immune cells (B and T cells) into the intestinal lamina propria. As a result, local levels of proinflammatory cytokines are elevated. The inflammatory response in UC may be further amplified by the recruitment of circulating leukocytes to the inflamed intestinal mucosa.3

The clinical course of UC is unpredictable and ranges from prolonged periods of remission to fulminant disease. Current research includes a focus on patients demonstrating primary nonresponse or loss of response over time.4

Signs & Symptoms

Signs and symptoms of UC may include:5,6

  • Diarrhea, often with blood or pus
  • Abdominal pain or discomfort
  • Fever
  • Fatigue
  • Nausea or loss of appetite
  • Painful, urgent bowel movements
  • Weight loss

Initially, patients tend to present with mild to moderate symptoms, although some patients will experience severe symptoms.6 Clinical course will vary between patients, with flare-ups of increased symptoms alternating with periods (sometimes extended) of mild or no symptoms.5

Certain complications may also occur as a result of UC, including anemia, dehydration, osteoporosis, toxic megacolon, increased risk of colon cancer, rectal pain or bleeding, and inflammation in other areas of the body.5

Risk Factors

UC affects about the same number of women as men. Risk factors may include:7

  • Age. UC usually begins before the age of 30 but can occur at any age, and some people may not develop the disease until after age 60.
  • Race or ethnicity. Whites have the highest risk of the disease, but UC can occur in any race. People of Ashkenazi Jewish descent are at a higher risk.
  • Family history. People have a higher risk if they have a close relative with the disease.

Disease & Clinical Trial Tools

Among many important factors, clinicians need to consider four distinct factors when assessing UC disease activity: clinical symptoms, quality of life, endoscopy, and histology. First, clinical parameters such as rectal bleeding and stool frequency are routinely assessed in clinical practice, and some physicians also evaluate symptoms such as urgency, incontinence, and nocturnal diarrhea. These factors are meaningful because patients consider them so. Another important indicator of disease activity is quality of life, which measures one’s ability to participate in normal social, occupational, and sexual activities. Lastly, disease activity can be assessed by endoscopy and histology. Individual assessment tools include the following:8

Mayo Score and Modified Mayo Endoscopic Score (MMES)

One of the most commonly used indexes to assess UC disease activity, the Mayo Score rates bleeding, stool frequency, physician assessment, and endoscopic appearance.9

The Modified Mayo Endoscopic Score (MMES) focuses on endoscopic activity in UC, evaluating both the severity and distribution of mucosal inflammation among five colon segments.10

Download Mayo Score and MMES

Ulcerative Colitis Endoscopic Index of Severity (UCEIS)

The Ulcerative Colitis Endoscopic Index of Severity (UCEIS) is used for evaluating the endoscopic severity of UC. With a range of 0 to 8, the score is simple to calculate and is composed of the sum of three descriptors: vascular pattern, bleeding, and erosions and ulcers.11,12

Download UCEIS

Nancy Histologic Index and Robarts Histopathology Index (RHI)

Nancy Histologic Index

Developed and validated to assess histological disease activity in UC,12 the Nancy Histologic Index grades ulceration, acute inflammatory infiltrate, and chronic inflammatory infiltrate on a scale of 0 to 4—with 0 indicating the absence of significant histological disease activity and 4 indicating severely active disease.12 The final score is determined by the worst feature present.13

Robarts Histopathology Index (RHI)

Also developed and validated to assess histological disease activity in UC, the RHI uses a scale of 0 to 3 to grade chronic inflammatory infiltrate, lamina propria neutrophils, neutrophils in the epithelium, and erosion or ulceration. The score, ranging from 0 to 33, is calculated as shown in the chart.13

Download RHI


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  2. Rubin D, Ananthakrishnan A, Siegel C, et al. ACG Clinical Guideline: Ulcerative Colitis in Adults. Am J Gastroenterol. 2019;114(3):384-413.
  3. Ordas I, Eckmann L, Talamini M, et al. Ulcerative colitis. Lancet. 2012;380:1606-1619.
  4. Roda G, Jharap B, Neeraj N, Colombel J-F. Loss of response to anti-TNFs: definition, epidemiology, and management. Clin Transl Gastroenterol. 2016;7:e135.
  5. Ulcerative Colitis. Cleveland Clinic. Published March 20, 2016. Accessed April 20, 2020.
  6. Ulcerative Colitis. National Institute of Diabetes and Digestive and Kidney Diseases. Published September 2014. Accessed April 20, 2020.
  7. Mayo Clinic. Accessed July 7, 2020.
  8. Walsh A, Travis S. Assessing disease activity in patients with ulcerative colitis. Gastroenterol Hepatol. 2012;8(11):751-754.
  9. Lewis JD, Shaokun C, Nessel L, et al. Use of the non-invasive components of the Mayo score to assess clinical response in ulcerative colitis. Inflamm Bowel Dis. 2008;14(12):1660-1666.
  10. Lobatón T, Bessissow T, De Hertogh G, et al. The Modified Mayo Endoscopic Score (MMES): a new index for the assessment of extension and severity of endoscopic activity in ulcerative colitis patients. J Crohn’s Colitis. 2015;9(10):846-852.
  11. Travis SPL, Schnell D, Krzeski P, et al. Reliability and initial validation of the ulcerative colitis edoscopic index of severity. Gastroenterology. 2013;145(5):987-995.
  12. Nakov RV, Nakov VN, Gerova VA, et al. Correlation between ulcerative colitis endoscopic index of severity, Lichtiger index and fecal calprotectin in ulcerative colitis patients. Intern Med. 2017;7(4):248.
  13. Marchal-Bressenot A, Salleron J, Boulagnon-Rombi C, et al. Development and validation of the Nancy histological index for UC. Gut. 2017;66:43-49.
  14. Pai RK, Jairath V, Vande Casteele N, et al. The emerging role of histologic disease activity assessment in ulcerative colitis. Gastrointest Endosc. 2018;88:887-898.