• Clinical science

Ulcerative colitis


Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) characterized by chronic mucosal inflammation of the rectum, colon, and cecum. Common symptoms include bloody diarrhea, abdominal pain, and fever. Laboratory findings typically show elevated inflammatory markers and the presence of autoantibodies (pANCA). Definitive diagnosis requires biopsies showing abnormal colonic mucosa and characteristic histopathology. Aminosalicylic acid derivatives are the mainstay of treatment, although severe episodes typically require corticosteroids and immunosuppressants to achieve remission. In the case of distal colitis, some drugs may be administered topically (e.g., via enema), whereas more proximal inflammation requires systemic treatment. Proctocolectomy is curative and indicated for complicated UC or dysplasia. Individuals with UC are predisposed to colorectal cancer and should thus undergo regular surveillance colonoscopy.


  • Prevalence
    • Approx. 600,000 adults in the U.S. are affected by UC [1]
    • Ethnicity
      • Higher in the white than in the black, Hispanic, or Asian populations
      • Highest among individuals of Ashkenazi Jewish descent.
    • Slightly higher in men than women [2]
  • Peak incidence
    • 15–35 years [3]
    • Another smaller peak may be observed in individuals > 55 years [4]

References: [4][5][2]

Epidemiological data refers to the US, unless otherwise specified.


Truelove and Witts severity index [6]

Criteria Mild Moderate Severe
Bowel movements/day < 4 4–6 > 6
Blood in stools Intermittent Frequent Continuous
Temperature < 37.5°C (99.5°F) ≤ 37.8°C (99.68°F) > 37.8°C (100.4°F)
Heart rate < 90/min ≤ 90/min > 90/min
Hemoglobin > 11.5 g/dL ≥ 10.5 g/dL < 10.5 g/dL
ESR < 20 mm/h ≤ 30 mm/h > 30 mm/h

Montreal classification of extent and severity of ulcerative colitis [7]

Disease extent/severity Localization/definition
E1: Ulcerative proctitis Mucosal involvement limited to the rectum
E2: Left-sided/distal ulcerative colitis Mucosal involvement limited to part of the colorectum distal to the splenic flexure
E3: Extensive ulcerative colitis/pancolitis Mucosal involvement extends to the proximal of the splenic flexure
S0: Clinical remission No mucosal involvement, asymptomatic
S1: Mild ulcerative colitis ≤ 4 stools/day (with or without blood), no signs of systemic illness, ESR normal
S2: Moderate ulcerative colitis > 4 stools/day, only minimal signs of systemic illness
S3: Severe ulcerative colitis ≥ 6 stools/day with blood, heart rate ≥ 90/min, temperature ≥ 37.5°C (99.5°F), Hb < 10.5 g/dL, ESR > 30 mm/h



The exact mechanism is unknown but studies suggest that ulcerative colitis is the result of abnormal interactions between host immune cells and commensal bacteria. [8][2]

The rectum is always involved in UC!

Risk factors [8][2][4]

Protective factors [8][2]

Clinical features

Intestinal symptoms

Extraintestinal symptoms

Primary sclerosing cholangitis (PSC) is often associated with inflammatory bowel disease, especially UC. However, only around 4% of people with inflammatory bowel disease develop PSC!

For the characteristics of ulcerative colitis, think “ULCCCERS”: Ulcers, Large intestine, Continuous/Colon cancer/Crypt abscesses, Extends proximally, Red diarrhea, Sclerosing cholangitis.

Course of the disease

  • Chronic intermittent
    • Most common course
    • Exacerbation is followed by complete remission.
  • Chronic continuous
    • Complete remission does not occur.
    • Severity of the disease varies.
  • Acute fulminant

Subtypes and variants

Backwash ileitis



Laboratory tests


Endoscopy (e.g., colonoscopy) with histological examination is considered the best test to definitively diagnose UC.

  • Typical findings: : See “Gross pathology” below.
  • Pattern of disease involvement [3]
  • Recommendations [3]
    • Evaluate the ileum to rule out Crohn disease
    • Stepwise biopsy (for findings, see "Pathology" below)
    • Colonoscopy is contraindicated in patients with acute flare because of the high risk of perforation but should be performed once symptoms improve.
      • Sigmoidoscopy may be considered as an alternative.

Observe caution in taking biopsies from patients with severe disease, as the risk of perforation is high.

Imaging [14][3]

Imaging studies may serve as useful adjunct diagnostic procedures for UC, particularly when it comes to detecting complications.



Gross pathology

  • Early stages
  • Chronic disease
    • Loss of mucosal folds
    • Loss of haustra
    • Strictures
    • Deep ulcerations
    • Pseudopolyps
      • Raised areas of normal mucosal tissue that result from repeated cycles of ulceration and healing
      • Ulceration → formation of granulation tissue → deposition of granulation tissue → epithelization
      • Morphologically resemble polyps but do not undergo neoplastic transformation
      • Found in advanced disease

In ulcerative colitis, the extent of intestinal inflammation is limited to the mucosa and submucosa. In contrast, Crohn disease shows a transmural pattern of intestinal involvement.

Histological findings

Noncaseating granulomas are seen in Crohn disease but are not a feature of ulcerative colitis!

Differential diagnoses

Differential diagnosis considerations

Microscopic colitis

The differential diagnoses listed here are not exhaustive.


Initially, UC is treated conservatively with drugs to induce and maintain disease remission. Curative proctocolectomy is generally indicated if medical therapy fails or complications arise.

General management

  • Rehydration
  • Supplementation of nutritional deficiencies (e.g., iron)
  • Supplementation of nutrition: severe cases may warrant consideration of a feeding tube or parenteral nutrition.

Medical therapy [3]

Supportive care

Mild disease

Moderate disease

Severe or refractory disease

Systemic corticosteroids should only be used for the treatment of an active flare and are not recommended as a maintenance medication for ulcerative colitis.

Surgical intervention

  • Goal
  • Indications
    • Emergent: Acute complications despite adequate conservative management (e.g., toxic megacolon, perforation, sepsis, uncontrolled bleeding, etc.)
    • Elective: epithelial dysplasia, severe relapses, long-term dependence on steroids, impairment of the patient's general condition
  • Procedure: proctocolectomy with an ileal pouch-anal anastomosis (IPAA or J pouch)
    • Resection of the entire colon and rectal mucosa while sparing the anal sphincters.
    • Loops of small intestine (serving as the pouch) are used to create an artificial rectum (reservoir for feces) and thus a continence-conserving connection between the ileum and anus.
  • Complications
    • Anastomotic leak
    • Pouchitis (↑ stool frequency, malaise, and possibly incontinence caused by bacterial overgrowth)

In contrast to Crohn disease, ulcerative colitis can be cured surgically (proctocolectomy).



We list the most important complications. The selection is not exhaustive.


On average, the life expectancy of patients with UC is normal.

last updated 11/22/2020
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