Introduction

Ulcerative colitis (UC) is a form of inflammatory bowel disease. Inflammation always starts at rectum (hence it is the most common site for UC), never spreads beyond ileocaecal valve and is continuous.

Epidemiology

  • Incidence: 10.00 cases per 100,000 person-years
  • Peak incidence: 20-30 years
  • Sex ratio: 1:1
Condition Relative
incidence
Colorectal cancer6.40
Crohn's disease1.10
Ulcerative colitis1
Microscopic colitis1.00
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Pathophysiology

Pathology
  • red, raw mucosa, bleeds easily
  • no inflammation beyond submucosa (unless fulminant disease)
  • widespread ulceration with preservation of adjacent mucosa which has the appearance of polyps ('pseudopolyps')
  • inflammatory cell infiltrate in lamina propria
  • neutrophils migrate through the walls of glands to form crypt abscesses
  • depletion of goblet cells and mucin from gland epithelium
  • granulomas are infrequent

Clinical features

The initial presentation is usually following insidious and intermittent symptoms. Features include:

Investigations

Bloods

Bloods may show raised inflammatory markers and anaemia.


Faecal calprotectin

Faecal calprotectin is a test for intestinal inflammation that has been recommended by NICE as a screening tool for inflammatory bowel disease (IBD). It can also be used to monitor the response to treatment in IBD patients.

In adults, it has a sensitivity of 93% and specificity of 96% for IBD. In children, the specificity falls to around 75%.

In addition to IBD, other causes of a raised faecal calprotectin include:
  • bowel malignancy
  • coeliac disease
  • infectious colitis
  • use of NSAIDs

Imaging

Barium enema
  • loss of haustrations
  • superficial ulceration, 'pseudopolyps'
  • long standing disease: colon is narrow and short -'drainpipe colon'

© Image used on license from Radiopaedia
Abdominal x-ray from a patient with ulcerative colitis showing lead pipe appearance of the colon (red arrows). Ankylosis of the left sacroiliac joint and partial ankylosis on the right (yellow arrow), reinforcing the link with sacroilitis.

© Image used on license from Radiopaedia
Barium enema from a patient with ulcerative colitis. The whole colon, without skips is affected by an irregular mucosa with loss of normal haustral markings.

Differential diagnosis

The two main types of inflammatory bowel disease are Crohn's disease and ulcerative colitis. They have many similarities in terms of presenting symptoms, investigation findings and management options.

Venn diagram showing shared features and differences between ulcerative colitis and Crohn's disease. Note that whilst some features are present in both, some are much more common in one of the conditions, for example colorectal cancer in ulcerative colitis

There are however some key differences which are highlighted in table below:

Crohn's disease (CD)Ulcerative colitis (UC)
FeaturesDiarrhoea usually non-bloody
Weight loss more prominent
Upper gastrointestinal symptoms, mouth ulcers, perianal disease
Abdominal mass palpable in the right iliac fossa
Bloody diarrhoea more common
Abdominal pain in the left lower quadrant
Tenesmus
Extra-intestinalGallstones are more common secondary to reduced bile acid reabsorption

Oxalate renal stones*
Primary sclerosing cholangitis more common
ComplicationsObstruction, fistula, colorectal cancerRisk of colorectal cancer high in UC than CD
PathologyLesions may be seen anywhere from the mouth to anus

Skip lesions may be present
Inflammation always starts at rectum and never spreads beyond ileocaecal valve

Continuous disease
HistologyInflammation in all layers from mucosa to serosa
  • increased goblet cells
  • granulomas
No inflammation beyond submucosa (unless fulminant disease) - inflammatory cell infiltrate in lamina propria
  • neutrophils migrate through the walls of glands to form crypt abscesses
  • depletion of goblet cells and mucin from gland epithelium
  • granulomas are infrequent
EndoscopyDeep ulcers, skip lesions - 'cobble-stone' appearanceWidespread ulceration with preservation of adjacent mucosa which has the appearance of polyps ('pseudopolyps')
RadiologySmall bowel enema
  • high sensitivity and specificity for examination of the terminal ileum
  • strictures: 'Kantor's string sign'
  • proximal bowel dilation
  • 'rose thorn' ulcers
  • fistulae
Barium enema
  • loss of haustrations
  • superficial ulceration, 'pseudopolyps'
  • long standing disease: colon is narrow and short -'drainpipe colon'

*impaired bile acid rebsorption increases the loss calcium in the bile. Calcium normally binds oxalate.

Management

Treatment can be divided into inducing and maintaining remission. NICE updated their guidelines on the management of ulcerative colitis in 2019.

The severity of UC is usually classified as being mild, moderate or severe:
  • mild: < 4 stools/day, only a small amount of blood
  • moderate: 4-6 stools/day, varying amounts of blood, no systemic upset
  • severe: >6 bloody stools per day + features of systemic upset (pyrexia, tachycardia, anaemia, raised inflammatory markers)

Inducing remission

Treating mild-to-moderate ulcerative colitis
  • proctitis
    • topical (rectal) aminosalicylate: for distal colitis rectal mesalazine has been shown to be superior to rectal steroids and oral aminosalicylates
    • if remission is not achieved within 4 weeks, add an oral aminosalicylate
    • if remission still not achieved add topical or oral corticosteroid
  • proctosigmoiditis and left-sided ulcerative colitis
    • topical (rectal) aminosalicylate
    • if remission is not achieved within 4 weeks, add a high-dose oral aminosalicylate OR switch to a high-dose oral aminosalicylate and a topical corticosteroid
    • if remission still not achieved stop topical treatments and offer an oral aminosalicylate and an oral corticosteroid
  • extensive disease
    • topical (rectal) aminosalicylate and a high-dose oral aminosalicylate:
    • if remission is not achieved within 4 weeks, stop topical treatments and offer a high-dose oral aminosalicylate and an oral corticosteroid

Severe colitis
  • should be treated in hospital
  • intravenous steroids are usually given first-line
    • intravenous ciclosporin may be used if steroid are contraindicated
  • if after 72 hours there has been no improvement, consider adding intravenous ciclosporin to intravenous corticosteroids or consider surgery


Maintaining remission

Following a mild-to-moderate ulcerative colitis flare
  • proctitis and proctosigmoiditis
    • topical (rectal) aminosalicylate alone (daily or intermittent) or
    • an oral aminosalicylate plus a topical (rectal) aminosalicylate (daily or intermittent) or
    • an oral aminosalicylate by itself: this may not be effective as the other two options
  • left-sided and extensive ulcerative colitis
    • low maintenance dose of an oral aminosalicylate

Following a severe relapse or >=2 exacerbations in the past year
  • oral azathioprine or oral mercaptopurine


Other points
  • methotrexate is not recommended for the management of UC (in contrast to Crohn's disease)
  • there is some evidence that probiotics may prevent relapse in patients with mild to moderate disease

Complications

Colorectal cancer

Overview
  • risk of colorectal cancer is significantly higher than that of the general population although studies report widely varying rates
  • the increased risk is mainly related to chronic inflammation
  • worse prognosis than patients without ulcerative colitis (partly due to delayed diagnosis)
  • lesions may be multifocal

Factors increasing risk of cancer
  • disease duration > 10 years
  • patients with pancolitis
  • onset before 15 years old
  • unremitting disease
  • poor compliance to treatment

Colonoscopy surveillance in inflammatory bowel disease patients should be decided following risk stratification.

Lower risk

5 year follow up colonoscopy
  • Extensive colitis with no active endoscopic/histological inflammation
  • OR left sided colitis
  • OR Crohn's colitis of <50% colon

Intermediate risk

3 year colonoscopy
  • Extensive colitis with mild active endoscopy/histological inflammation
  • OR post-inflammatory polyps
  • OR family history of colorectal cancer in a first degree relative aged 50 or over

Higher risk

1 year follow up colonoscopy
  • Extensive colitis with moderate/severe active endoscopic/histological inflammation
  • OR stricture in past 5 years
  • OR dysplasia in past 5 years declining surgery
  • OR primary sclerosing cholangitis / transplant for primary sclerosing cholangitis
  • OR family history of colorectal cancer in first degree relatives aged <50 years