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# Ulcerative colitis

Ulcerative colitis is a chronic inflammatory bowel disease of the colon lining, starting in the rectum; it causes flares of bloody diarrhoea.

Updated 2026-10-29

## Structures involved

Tap one to see what it is and open it in 3D.

- [Rectum](https://durgical.com/en/anatomy/rectum/)
- [Sigmoid colon](https://durgical.com/en/anatomy/sigmoid-colon/)
- [Descending colon](https://durgical.com/en/anatomy/descending-colon/)
- [Transverse colon](https://durgical.com/en/anatomy/transverse-colon/)
- [Ascending colon](https://durgical.com/en/anatomy/ascending-colon/)
- [Cecum](https://durgical.com/en/anatomy/cecum/)
- [Colic arteries](https://durgical.com/en/anatomy/right-colic-artery/)
- [Inferior mesenteric artery](https://durgical.com/en/anatomy/inferior-mesenteric-artery/)

## In biochemistry

- [Carcinoembryonic antigen (CEA)](https://durgical.com/en/biochemistry/topics/carcinoembryonic-antigen/)

## In immunology

- [HLA associations with disease](https://durgical.com/en/immunology/hla-associations-with-disease/)
- [IL-10 and TGF-β (the brakes)](https://durgical.com/en/immunology/il-10-and-tgf/)
- [IL-12 and IL-23](https://durgical.com/en/immunology/il-12-and-il-23/)
- [TNF-α](https://durgical.com/en/immunology/tnf/)

## In histology

- [Large intestine, appendix and anal canal](https://durgical.com/en/histology/large-intestine-appendix-and-anal-canal/)

## Why it happens

- [Chronic inflammation: causes, cells and features](https://durgical.com/en/general-pathology/chronic-inflammation-causes-cells-and-features/)
- [Dysplasia and carcinoma in situ](https://durgical.com/en/general-pathology/dysplasia-and-carcinoma-in-situ/)
- [Precancerous conditions: when chronic inflammation, metaplasia or hyperplasia raise the risk](https://durgical.com/en/general-pathology/precancerous-conditions-when-chronic-inflammation-metaplasia-or-hyperplasia-rais/)
- [Multistep carcinogenesis: the adenoma–carcinoma sequence](https://durgical.com/en/general-pathology/multistep-carcinogenesis-the-adenoma-carcinoma-sequence/)
- [Enteroendocrine cells and GALT](https://durgical.com/en/histology/enteroendocrine-cells-and-galt/)

## What it is

Chronic inflammatory bowel disease in which inflammation of the colon's mucosa starts in the rectum and extends continuously upwards, causing bloody diarrhoea in relapsing flares.

## Who gets it

Usually begins in young adults, with a second smaller peak later in life. Its incidence is rising in Latin America, and in Colombian and regional series it is generally reported more often than Crohn disease.

## Causes

- Abnormal immune response to gut bacteria in genetically susceptible people
- Defects of the mucosal barrier
- Environmental factors and microbiome changes

## Risk factors

- Family history of inflammatory bowel disease
- Being a former smoker (smoking appears protective, but is never advised)
- Primary sclerosing cholangitis
- Urban, industrialised lifestyle

## Pathophysiology

Inflammation is limited to the mucosa and submucosa and is continuous, starting at the rectum. The mucosa becomes friable with ulcers and crypt abscesses, and long-standing disease causes pseudopolyps and loss of haustra. Chronic inflammation raises the risk of dysplasia and colorectal cancer.

## Classification

- Montreal extent: proctitis (E1), left-sided colitis (E2), extensive colitis (E3)
- Severity: mild, moderate, severe (Truelove and Witts criteria, Mayo score)

## Symptoms and signs

- Bloody diarrhoea with mucus
- Urgency and tenesmus
- Crampy lower abdominal pain, often relieved by defecation
- In severe flares: fever, tachycardia, weight loss, anaemia
- Extraintestinal: arthritis, erythema nodosum, pyoderma gangrenosum, episcleritis, uveitis, primary sclerosing cholangitis

## Red flags

- Acute severe colitis: frequent bloody stools with fever, tachycardia, anaemia or high inflammatory markers
- Abdominal distension and pain (toxic megacolon)
- Peritonitis (perforation)
- Heavy bleeding

## Diagnosis

**Clinical**
Recurrent bloody diarrhoea with urgency; examination for signs of severe disease.

**Tests**
Stool cultures and Clostridioides difficile testing to exclude infection; amoebiasis in endemic areas. Full blood count, CRP, albumin, faecal calprotectin. Colonoscopy with biopsies shows continuous inflammation from the [rectum](https://durgical.com/en/anatomy/rectum/), crypt abscesses and architectural distortion.

**Imaging**
Plain abdominal X-ray in severe flares to look for toxic megacolon (a [transverse colon](https://durgical.com/en/anatomy/transverse-colon/) wider than about 6 cm is commonly cited). CT if perforation is suspected.

## Differential diagnosis

- Crohn colitis
- Infectious colitis (bacterial, amoebic, C. difficile)
- Ischaemic colitis
- Colorectal cancer
- Radiation or drug-induced colitis

## Goal of treatment

Induce and maintain remission with healing of the mucosa, avoid long-term corticosteroids, prevent complications and detect dysplasia early.

## Treatment

**Medical**
Aminosalicylates (5-ASA), oral and rectal, for mild to moderate disease and maintenance.

**Medical**
Corticosteroids for flares (oral or rectal; intravenous in acute severe colitis), not for maintenance.

**Medical**
Immunomodulators (thiopurines) and biologic therapy (anti-TNF, anti-integrin, anti-interleukin agents) for moderate to severe or steroid-dependent disease.

**Medical**
Small molecules (JAK inhibitors, S1P receptor modulators) as further options.

**Acute**
Rescue therapy in acute severe colitis (anti-TNF or a calcineurin inhibitor) with joint medical and surgical care.

**Surgical**
Proctocolectomy, often with an ileal pouch-anal anastomosis, for refractory disease, dysplasia or cancer; it cures the bowel disease.

**Follow-up**
Surveillance colonoscopy, usually starting about eight years after onset (earlier with primary sclerosing cholangitis).

## Drugs for this condition

- [Hydrocortisone](https://durgical.com/en/pharmacology/hydrocortisone/)
- [Mesalazine](https://durgical.com/en/pharmacology/mesalazine/)
- [Sulfasalazine](https://durgical.com/en/pharmacology/sulfasalazine/)
- [Azathioprine](https://durgical.com/en/pharmacology/azathioprine/)
- [Adalimumab](https://durgical.com/en/pharmacology/adalimumab/)
- [Infliximab](https://durgical.com/en/pharmacology/infliximab/)
- [Golimumab](https://durgical.com/en/pharmacology/golimumab/)
- [Ustekinumab](https://durgical.com/en/pharmacology/ustekinumab/)
- [Tofacitinib](https://durgical.com/en/pharmacology/tofacitinib/)

## Complications

- Toxic megacolon and perforation
- Severe bleeding
- Colorectal cancer (risk grows with extent and duration)
- Primary sclerosing cholangitis
- Anaemia, osteoporosis (from steroids), venous thromboembolism
- Pouchitis after surgery

## Prognosis

Relapsing and remitting; most patients have mild to moderate disease controlled with medicines. Some need colectomy, which cures the colitis. Life expectancy is close to normal.

## Prevention

- Adherence to maintenance therapy to prevent flares
- Regular surveillance colonoscopy for dysplasia

## Test yourself

Think of the answer, then tap the question to see it.

## Where does ulcerative colitis start and how does it extend?

It always involves the rectum and extends continuously upwards through the colon, without skip lesions.

## Which layer of the bowel wall does ulcerative colitis affect?

The mucosa (and superficial submucosa), unlike the transmural inflammation of Crohn disease.

## Which first-line drug class treats mild to moderate ulcerative colitis?

Aminosalicylates (5-ASA), given orally and rectally.

## Which liver disease is classically associated with ulcerative colitis?

Primary sclerosing cholangitis, which also raises the colorectal cancer risk.

## What is a feared complication of acute severe ulcerative colitis?

Toxic megacolon, with risk of perforation; it needs urgent medical and surgical assessment.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/ulcerative-colitis/)

## Related conditions

- [Crohn disease](https://durgical.com/en/conditions/crohn-disease/)
- [Colorectal cancer](https://durgical.com/en/conditions/colorectal-cancer/)
- [Ankylosing spondylitis](https://durgical.com/en/conditions/ankylosing-spondylitis/)
- [Irritable bowel syndrome](https://durgical.com/en/conditions/irritable-bowel-syndrome/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Ulcerative Colitis](https://www.ncbi.nlm.nih.gov/books/NBK459282/) (StatPearls (NCBI Bookshelf), 2023).

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Source: https://durgical.com/en/conditions/ulcerative-colitis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/ulcerative-colitis/