inflammatory bowel disease (IBD) characterized by chronic mucosal inflammation of the rectum, colon, and cecum. Common symptoms include bloody diarrhea, abdominal pain, and fecal urgency. Laboratory findings typically show elevated inflammatory markers (e.g., ESR, CRP) and elevated fecal calprotectin. Although not required for diagnosis, the presence of perinuclear antineutrophil cytoplasmic autoantibodies (pANCA) is suggestive of ulcerative colitis. Definitive diagnosis requires endoscopy, which may show changes to superficial vascular patterns, friable mucosa, and erosions and/or ulcerations. 5-Aminosalicylic acids (e.g., mesalamine) are the mainstay of treatment for mild-to-moderate disease. Patients who experience severe episodes often require corticosteroids or other immunosuppressants to achieve remission. In distal colitis, medications may be administered rectally (e.g., via enema), whereas more proximal inflammation requires oral treatment. Proctocolectomy is curative and indicated in patients with complicated ulcerative colitis or dysplasia. Patients with ulcerative colitis are at increased risk of developing colorectal cancer and should undergo regular endoscopic surveillance.is an
- 15–35 years of age 
- Another smaller peak may be observed in individuals > 55 years of age. 
- Similar for men and women 
Epidemiological data refers to the US, unless otherwise specified.
Risk factors 
- Genetic predisposition (e.g., )
- Ethnicity (White populations, individuals of Ashkenazi Jewish descent)
- Family history of inflammatory bowel disease
- Episodes of previous intestinal infection
- Increased fat intake (especially saturated fat and animal fat)
- Oral contraceptive use
- NSAIDs may exacerbate ulcerative colitis.
Protective factors 
Classification of ulcerative colitis by disease extent 
The extent of disease is classified based on endoscopic findings.
|Montreal classification for the extent of ulcerative colitis|
|Disease extent||Mucosal involvement|
|Ulcerative proctitis (E1)||Limited to the rectum|
|Left-sided ulcerative colitis (E2)||Limited to the colon distal to the splenic flexure|
|Extensive ulcerative colitis (E3)||Extends proximal to the splenic flexure|
Classification of ulcerative colitis by severity 
There are several classification systems that can be used to assess disease severity. Criteria include:
- Ulcerative colitis endoscopic index of severity (UCEIS)
- Mayo endoscopic score 
- Clinical presentation
- A combination of both endoscopic findings and clinical presentation
- Other: response to medication, disease course, and the patient's quality of life
- Remission criteria (ACG): no diarrhea, no visible blood in stools, no fecal urgency, fecal calprotectin < 150–200 mcg/g, normal laboratory values, and normal endoscopy findings 
|American College of Gastroenterology ulcerative colitis activity index |
|Criteria||Severity of ulcerative colitis|
|Stools per day||< 4|| |
|Frequency of blood in stool||Intermittent||Frequent||Continuous|
|Fecal urgency||Mild, occasional||Often||Continuous|
|Hemoglobin||Normal||< 75% of normal||Transfusion required|
|ESR||< 30 mm/hour||> 30 mm/hour|
|Fecal calprotectin||> 150–200 mcg/g|
|Mayo endoscopy score||1||2–3||3|
|Ulcerative colitis endoscopic index of severity||2–4||5–8||7–8|
|Truelove and Witts severity index |
|Bowel movements per day||≤ 4||≥ 6|
|Amount of blood in stool||Small amount||Macroscopic blood|
|Temperature||No fever||≥ 37.8°C (100.4°F)|
|Heart rate||No tachycardia||> 90 bpm|
|Hemoglobin||No severe anemia||≤ 75% of normal|
|ESR||≤ 30 mm/hour||> 30 mm/hour|
Treatment recommendations by the ACG are based on the ACG ulcerative colitis activity index, while recommendations by the American Gastroenterological Association (AGA) are based on a combination of the Truelove and Witts severity index and the Mayo score for ulcerative colitis activity. There is significant overlap among the criteria used in all ulcerative colitis severity indices.
- Dysregulation of intestinal epithelium: increased permeability for luminal bacteria → activation of macrophages and dendritic cells → antigen presentation to macrophages and naive CD4+ cells leads to:
- Dysregulation of the immune system: upregulation of lymphatic cell activity (T cells, B cells, plasma cells) in bowel walls → enhanced immune reaction and cytotoxic effect on colonic epithelium → inflammation with local tissue damage (ulcerations, erosions, necrosis) in the submucosa and mucosa
- Pattern of involvement
Extraintestinal symptoms of ulcerative colitis
- General: fatigue, fever
- Skeletal: (most common extraintestinal manifestation of ulcerative colitis): sacroiliitis, , 
- Ocular: , episcleritis, iritis
- Biliary: primary sclerosing cholangitis (it is rare for patients with ulcerative colitis to develop PSC, but up to 90% of all patients with PSC will also have ulcerative colitis)
- In children and adolescents: growth retardation and delayed puberty
Subtypes and variants
- Definition: inflammation of the terminal ileum in the context of ulcerative colitis
- Epidemiology: affects approximately 10–20% of all patients diagnosed with ulcerative colitis
- Localization: typically affects an area a few centimeters proximal to the ileocecal valve
- Pathophysiology: The pathological mechanism is not fully understood.
- Differential diagnosis: Clinically, backwash ileitis is hardly relevant but its presence makes it harder to differentiate between ulcerative colitis and Crohn disease.
- Evaluate patients with hematochezia and fecal urgency for ulcerative colitis.
- Rule out .
- Consult gastroenterology for ileocolonoscopy with histological examination to:
- Definitively diagnose ulcerative colitis
- Determine the and
- Identify signs of acute severe ulcerative colitis (ASUC).
- Consider CT or MRI abdomen if direct endoscopy is contraindicated.
- Assess for the presence of .
Laboratory studies 
Stool testing for causes of gastroenteritis is indicated in all patients. Blood tests are not routinely required for diagnosis but help assess disease activity and severity.
- CBC: anemia, leukocytosis, thrombocytosis 
- ESR, CRP: Elevated levels may indicate active ulcerative colitis and often correlates with disease severity.
- Hypoalbuminemia: associated with a poor prognosis and more severe disease 
- ALP, GGT: elevated in patients with concurrent
Perinuclear ANCA (pANCA) 
- Not routinely recommended
- Elevated in up to 70% of patients with ulcerative colitis
- Stool diagnostic studies
Hypoalbuminemia and elevated CRP suggest a poor prognosis. Other poor prognostic factors include < 40 years of age at diagnosis, extensive ulcerative colitis, and severe disease based on endoscopic evaluation scores. 
- Recommended method for diagnosis and disease monitoring 
- Severe disease is a relative contraindication.
|Endoscopic findings in ulcerative colitis|
|Early stages||Chronic disease|
- EGD: recommended for patients with upper gastrointestinal symptoms to rule out Crohn disease
Imaging studies are not routinely recommended; for diagnosing ulcerative colitis but may be used as an adjunct to endoscopy, particularly for the detection of complications; , or if endoscopy is not possible. 
Abdominal x-rays 
- Indication: initial and serial evaluation of suspected ASUC
- Typically normal in mild-to-moderate disease
- Loss of colonic haustra (lead pipe appearance) may be seen in severe cases
- May show signs of complications, e.g.:
CT or MRI abdomen 
Barium enema radiography 
The role of barium enema is limited, as it is less sensitive than other imaging modalities and is contraindicated in patients with obstruction or perforation.
- Indication: : can be considered for assessment of the proximal colon if colonoscopy is contraindicated
Abdominal ultrasound 
- Indication: monitoring disease activity and treatment response
- Findings: increased bowel wall thickness
See “Endoscopic findings in ulcerative colitis” in “Diagnostics.”
- Early stages
- Chronic disease
Differential diagnosis considerations
- Crohn disease (see “ ”)
- Exudative-inflammatory diarrhea
- Ischemic colitis
- Infectious colitis
- Radiation colitis
- Celiac disease
- Inflammatory diarrhea
Microscopic colitis 
- Definition: : an idiopathic, inflammatory form of colitis that is characterized by a normal macroscopic appearance of bowel on colonoscopy and collagenous or lymphocytic infiltrates on microscopy
- Histological subtypes
- Epidemiology 
- Etiology: unknown
- Risk factors
- Clinical features
The differential diagnoses listed here are not exhaustive.
- Choose medical therapy based on disease severity and disease extent.
- If remission is achieved, initiate maintenance therapy.
- If remission is not achieved, escalate treatment.
- Monitor for complications related to the disease and treatment.
- Consult surgery for consideration of curative proctocolectomy if medical therapy is unsuccessful or complications occur.
- Screen for colorectal cancer and other common comorbidities (e.g., depression and anxiety).
While many patients with ulcerative colitis can be managed in an outpatient setting, patients with should be managed in the inpatient setting.
Management of acute severe ulcerative colitis
- The presence of both of the following indicates acute severe ulcerative colitis (ASUC): 
- Admit all patients with ASUC to the hospital.
- Obtain a stool test for CDI.
- Consult gastroenterology to obtain urgent flexible sigmoidoscopy (ideally within 24 hours) and discuss management.
- Initiate treatment with IV corticosteroids (see “Induction of remission”).
- Provide supportive care with and as needed.
- Initiate . 
- Closely monitor for:
- Consult surgery if:
Pharmacological therapy 
- Pharmacological therapy is used to induce and maintain disease remission.
- Goals of treatment
- Initially: symptomatic remission 
- Long-term: mucosal healing
Induction of remission
While treatment recommendations are based on mild-to-moderate, moderate-to-severe, and acute severe disease severity, the ACG ulcerative colitis activity index classifies disease severity as mild, moderate-to-severe, or fulminant.
|Medications for induction of remission in ulcerative colitis |
|Acute severe ulcerative colitis|
Azathioprine may be considered in combination with anti-TNF therapy for induction of remission or as monotherapy for maintenance of remission; it is not recommended as monotherapy for induction of remission. 
Overview of 5-ASA and 5-ASA derivatives 
|5-ASA and 5-ASA derivatives|
|Description||Mechanism of action||Adverse effects|
|Mesalamine|| || |
Supportive therapy 
- Treat pain as needed.
- Avoid parenteral nutrition unless required to improve nutritional status prior to colectomy. 
- Identify and treat any micronutrient deficiency.
- Currently, there is insufficient evidence to support the use of probiotics. 
Surgical treatment 
- Procedure: : restorative proctocolectomy with an ileal pouch-anal anastomosis (IPAA or J pouch)
- Complications of surgery
- Disease monitoring
- Colorectal cancer screening 
↑ Risk of cancer (see ”Long-term management” in “Treatment” for screening protocol)
- Risk increases with duration and/or extent of disease (e.g., pancolitis).
- colitis. risk is not significantly increased in patients with mild ulcerative
- Fulminant colitis: severe bowel inflammation that typically causes > 10 stools per day, lower gastrointestinal bleeding, abdominal pain, and abdominal distention
- (both acute and chronic)
- Perforation → peritonitis (see “”)
- Colonic stricture
We list the most important complications. The selection is not exhaustive.
Special patient groups
Inflammatory bowel disease in pregnancy 
- Fertility is not affected in women with IBD in remission and no history of abdominal surgery.
- Women with active disease have decreased fertility rates.
- Pharmacological therapy for IBD does not impact fertility.
- Active disease at conception increases the risk of persistently active disease during gestation.
- Active disease is associated with an increased risk of preterm birth and low birth weight.
- Patients who wish to conceive should be on appropriate pharmacological therapy to maintain disease remission.
- With the exception of methotrexate, all other treatments can be continued at conception.
Disease management during pregnancy
- Most medications used in the treatment of IBD are considered safe during pregnancy.
- Corticosteroids; are indicated for disease flares but should be avoided as maintenance therapy because of the increased risk of gestational diabetes, preterm birth, and low birth weight.
- 5-ASA, 5-ASA derivatives, immunomodulators, and biopharmaceuticals can be used during pregnancy.
- Monotherapy is preferred for maintenance treatment to reduce the risk of adverse effects.