Crohn's disease

Question 1

Define Crohn’s disease and summarise its aetiology and epidemiology.

Answer 1

Definition: Chronic granulomatous inflammatory disease that can affect any part of GI tract. Grouped with UC as an IBD

Aetiology/risk factors: Unknown but maybe due to interplay between environment and genetics. Inflammation can occur anywhere but 40% involves the terminal ileum.

Epidemiology:

• UK annual incidence: 5-8/100,000
• UK prevalence: 50-80/100,000
• Affects any age (peaks in teens, 20s and 40s)

Question 2

Describe the history/presenting symptoms of Crohn’s disease

Answer 2

• Crampy abdominal pain (due to inflammation, fibrosis or bowel obstruction).
• Diarrhoea (may be bloody or Steatorrhoea).
• Fever, malaise, weight loss.
• Symptoms of complications.
• Sometimes right iliac fossa pain due to inflammation of terminal ileum.

Question 3

What are the signs of Crohn’s disease upon physical examination?

Answer 3

• Weight loss
• Clubbing
• Signs of anaemia
• Aphthous ulcers in mouth
• Perianal skin tags, fistulae and abscesses
• Uveitis, erythema nodosum, pyoderma gangernosum

Question 4

What investigations are used to identify Crohn’s disease?

Answer 4

• Blood: FBC- (low Hb, high platelets, high WCC), U&Es, LFTs- (low albumin), high ESR (suggests chronic inflammation), CRP may be high or normal.
• Stool microscopy and culture: exclude infective colitis.
• AXR: for evidence of toxic megacolon.
• Erect CXR: if risk of perforation.
• Small bowel barium follow-through: May reveal fibrosis/strictures (string sign of kantor), deep ulceration (rose thorn ulcers), cobblestone mucosa.
• Endoscopy: May help to differentiate between UC and CD, useful for malignancy monitoring + disease progression. Can show mucosal oedema + ulceration, fistulae + abscesses, transmural chronic inflammation with infiltration of macrophages, lymphocytes and plasma cells.
• Radionuclide-labelled neutrophil scan: localization of inflammation (when other tests are contraindicated)

Question 5

How is Crohn’s disease acutely managed?

Answer 5

In acute exacerbation of the disease:

• Fluid resuscitation
• IV/oral corticosteroids
• 5- ASA analogues
• Analgesia
• Parenteral nutrition may be necessary
• Monitor markers of disease activity e.g. fluid balance, ESR, CRP, platelets, Hb.

Question 6

How is Crohn’s disease managed in the long term?

Answer 6

• Steroids- for acute exacerbations.
• 5-ASA analogues- (e.g. sulfasalazine, mesalazine) decreases relapse frequency (useful for mild-moderate disease)
• Immunosuppression- using steroid-sparing agents (e.g. azathioprine, 6-mercaptopurine, methotrexate) decreases relapse frequency.
• Anti-TNF agents- (e.g. infliximab, Adalimumab) very effective at inducing and maintaining remission. Usually reserved for refractory Crohn’s

Question 7

What are the other ways in which Crohn’s disease managed?

Answer 7

-General advice: stop smoking and dietician referral (low fibre diet if stricture present), education and advice.

-Surgery: Indicated if:
   > Medical treatment fails
   > Failure to thrive in children.
   > Involves resection of affected bowel and stoma formation.
   > Risk of disease recurrence.

Question 8

What are the complications of Crohn’s disease?

Answer 8

• GI: Haemorrhage, strictures, perforation, fistulae, perianal fistulae and abscesses, GI cancer, malabsorption.
• Extra intestinal features: Uveitis, episcleritis, gallstones, kidney stones, arthropathy, sacroiliitis, ankylosing spondylitis, erythema nodosum, pyoderma gangrenosum, amyloidosis.

Question 9

Summarise the prognosis for patients with Crohn’s disease

Answer 9

• It is a chronic relapsing condition.
• 2/3 of patients will require surgery at some stage.
• 2/3 of the patients require >1 operation.