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Inflammatory Bowel Disease

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Overview

Inflammatory bowel disease (IBD) is an umbrella term describing inflammation of the small intestine and colon. Crohn’s disease (CD) and ulcerative colitis (UC) are the main two types, although other conditions such as Behçet’s disease can also cause IBD. In up to 20% of patients, it is difficult to differentiate between CD and UC, and sometimes an initial diagnosis of indeterminate colitis may be made.

Presentation

General features

CD and UC may present with similar features:

Features suggesting Crohn’s disease

Features suggesting Crohn’s disease are:

  • Diarrhoea does not usually contain as much blood as UC
  • Fever is often present
  • Tenesmus (the feeling of needing to pass stools even though the bowel is empty) is less common
  • Weight loss is more common
  • Fistulae is more common
  • CD can affect any part of the gastrointestinal (GI) tract from mouth to anus (e.g. mouth ulcers)

Features suggesting ulcerative colitis

Features suggesting ulcerative colitis are:

  • Diarrhoea often contains mucus and blood
  • Fever is sometimes present, usually if a UC flare is severe
  • Tenesmus is more common
  • Weight loss is less common than in CD
  • Fistulae is less common than in CD
  • UC only affects the colon and rectum

Investigations

Overview

  • Full blood count:
    • May show anaemia which can be due to chronic inflammation, blood loss, or iron/B12/folate malabsorption
    • Increased white cells suggest acute or chronic inflammation
    • Increased platelets suggest active inflammation
  • Iron studies:
    • To identify iron deficiency
  • Haematinics:
    • To assess serum B12 and folate:
  • C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR):
    • Elevated in inflammation
  • Stool testing:
  • Faecal calprotectin:
    • A non-specific marker released from neutrophils in gastrointestinal tract inflammation
    • Can help with differentiating IBD from irritable bowel syndrome (IBS)
  • Colonoscopy with biopsies:
    • The diagnostic test. CD and UC have differing features.

Endoscopic features suggesting CD

  • Skip lesions (patchy inflammation) anywhere from the mouth to the anus
  • Perianal disease is more common than in UC
  • Inflammation is in all layers (transmural) of GI tissue
  • Histology shows Goblet cells and granulomas

Endoscopic features suggesting UC

  • Inflammation is continuous anywhere from the ileocaecal valve to the rectum
  • Perianal disease is less common than in CD
  • Inflammation is more shallow, usually affecting the superficial mucosa
  • Histology shows crypt abscesses

Complications

Overview

  • Anaemia:
    • Occurs due to malabsorption and blood loss
  • Intestinal obstruction – more common in CD
    • Occurs due to bowel wall thickening during acute inflammation
  • Malabsorption, malnutrition, and dehydration – seen in CD, not UC:
    • Inflammation of the small bowel can damage the intestinal mucosa, which can lead to reduced absorption
  • Colorectal cancer 

Extra-intestinal manifestations related to disease activity

These include:

  • Pauci-articular arthritis – the most common extra-intestinal manifestation of IBD
    • Arthritis affecting <5 large joints (e.g. shoulders, elbows, wrists, hips, or knees) 
    • Usually asymmetric, lasts for weeks, and does not usually cause permanent damage
    • There may be associated enthesitis (inflammation where a tendon attaches to a bone), tenosynovitis (inflammation of a tendon or its sheath), or dactylitis (inflammation of an entire finger/toe)
  • Erythema nodosum:
    • Usually on the anterior tibia or extensor surfaces of the legs
  • Mouth ulcers:
    • More common in CD
  • Episcleritis:
    • More common in CD
    • Red eye with injected sclera and conjunctiva
    • Classically painless, but can have some discomfort, itching, or burning
  • Metabolic bone disease (e.g. osteoporosis, osteopenia, osteomalacia):
    • May be due to malabsorption, inflammation, or corticosteroid treatment

Extra-intestinal manifestations unrelated to disease activity

These include:

  • Ankylosing spondylitis:
    • Presents as lower back pain which can radiate into the buttocks
  • Polyarthritis:
    • Affecting ≥5 joints, such as the small joints of the hands
    • Usually symmetrical and can leave permanent damage
  • Pyoderma gangrenosum:
    • Most commonly seen on the shins and at sites of previous trauma
  • Psoriasis
  • Anterior uveitis:
    • More common in UC
    • Usually bilateral and insidious in onset
    • Presents as a painful red eye with blurred vision, photophobia, and headaches
  • Primary sclerosing cholangitis:
    • More common in UC
  • Gallstones:
    • More common in CD:
    • Occurs due to malabsorption of bile acids due to ileitis
    • Since UC does not affect the ileum, this is less common

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