Crohn's Disease Flashcards
Define
Chronic granulomatous inflammatory disease that can affect any part of the gastrointestinal tract. Grouped with ulcerative colitis and known, together, as inflammatory bowel disease.
Causes
- Cause unknown but thought to be due to interplay between genetic and environmental factors
- Though inflammation can occur anywhere from mouth to anus, 40% involves the terminal ileum
Risk Factors
mutation of NOD2/CARD15 gene ↑risk
smoking ↑risk x4, altered cell mediated immunity, NSAIDs may exacerbate
Epidemilogy
UK annual incidence: 5-8/100,000
UK prevalence: 50-80/100,000
Affects any age but peaks in teens, 20s and 40s
F>M, lower prevalence in Asian
Symptoms
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
Signs
Weight loss
Clubbing
Signs of anaemia
Aphthous ulcers in mouth
Perianal skin tags, fistulae and abscesses
Uveitis, erythema nodosum, pyoderma gangrenosum
Investigations
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: could show evidence of toxic megacolon
Erect CXR: if there is a risk of perforation
Small bowel barium follow-through could show:
- Fibrosis/strictures (string sign of Kantor - part of the intestine looks like a piece of string, showing incomplete filling of the intestinal lumen)
- Deep ulceration (rose thorn ulcers)
- Cobblestone mucosa
Endoscopy (OGD, colonoscopy) and biopsy may show:
- Could help differentiate UC and CD
- Useful for monitoring malignancy and disease progression
- Can show mucosal oedema and ulceration with ‘rose thorn fissures’ (occurs when there is a cobblestone mucosa)
- Fistulae and abscesses
- Transmural chronic inflammation with infiltration of macrophages, lymphocytes and plasma cells
- Granulomas with epithelioid giant cells may be seen in blood vessels and lymphatics
Radionucide-labelled neutrophil scan: can localise the inflammation (when other investigations are contraindicated)
Management
Acute Exacerbation
- Fluid resuscitation
- IV/oral corticosteroids
- 5-ASA analogues (e.g. mesalazine and olsalazine)
- Analgesia
- Parenteral nutrition may be necessary
- Monitor markers of disease activity e.g. fluid balance, ESR, CRP, platelets, Hb
Long-Term
- Steroids - for acute exacerbations
- 5-ASA analogues - decreases the frequency of relapses (useful for mild to moderate disease)
NOTE: more commonly used in UC
Immunosuppression: using steroid-sparing agents (e.g. azathioprine, 6-mercaptopurine, methotrexate) reduces the frequency of relapses
Anti-TNF agents: (e.g. infliximab and adalimumab) - very effective at inducing and maintaining remission. Usually reserved for refractory Crohn’s.
General Advice:
- Stop smoking
- Dietician referral (low fibre diet necessary if there are stricture present)
Surgery indicated it:
- Medical treatment fails
- Failure to thrive in children in the presence of complications
- Involves resection of affected bowel and stoma formation - NOTE: there is a risk of disease recurrence
Complicaitons
GI:
- Haemorrhage
- Strictures
- Perforation
- Fistulae (between bowel, bladder, vagina)
- Perianal fistulae and abscesses
- GI cancer
- Malabsorption
Extraintestinal Features:
- Uveitis
- Episcleritis
- Gallstones
- Kidney stones
- Arthropathy
- Sacroiliitis
- Ankylosing spondylitis
- Erythema nodosum
- Pyoderma gangrenosum
- Amyloidosis
Prognosis
- It is a chronic relapsing condition
- 2/3 of patients will require surgery at some stage
- 2/3 of these patients require more than 1 operation
