Crohn's Disease

Question 1

Define Crohn’s disease.

Answer 1

Chronic granulomatous inflammatory disease that can affect any part of the gastrointestinal tract. Grouped with ulcerative colitis and together they are known as inflammatory bowel disease.

Question 2

Describe the epidemiology of Crohn’s disease.
•Incidence
•Prevalence
•Effect of age

Answer 2

Annual UK incidence is 5–8 in 100,000.

Prevalence is 50–80 in 100,000.

Affects any age but peak incidence is in the teens or twenties.

Question 3

Give a brief overview of the pathology of Crohn’s disease.

Answer 3

Small bowel (terminal ileum) = most affected site, followed by peritoneum (leading to anal sepsis) and then the colon (Crohn’s colitis):
•Transmural inflammation can cause fistulae
•Skip lesions common
•Mucosal oedema and fibrosis can cause strictures and then small bowel obstruction
•Non-caseating granulomas are pathognomonic (not always present)

Question 4

List the potential causes of Crohn’s disease.

Answer 4

Cause has not yet been elucidated, but thought to involve an interplay between genetic and environmental factors;
•Twin studies: identified the gene NOD2
•Infection: Current thought implicates a bacterial infection.
•Environmental: cigarette smoking triples risk, diets high in sugar and low in fibre are implicated

Inflammation can occur anywhere along GI tract (40% involving the terminal ileum) and ‘skip’ lesions with inflamed segments of bowel interspersed with normal segments is not unusual.

Question 5

What would a patient with Crohn’s complain of in a history?

Answer 5

Crampy abdominal pain (caused by inflammation, fibrosis or bowel obstruction).
Diarrhoea (may be bloody or steatorrhoea).
Fever, malaise, weight loss.
Symptoms of complications.

Question 6

What could you find on examination of a patient with Crohn’s disease?

Answer 6

Weight loss, clubbing, signs of anaemia.

Aphthous ulceration of the mouth.

Perianal skin tags, fistulae and abscesses.

Signs of complications (eye disease, joint disease, skin disease).

Question 7

What investigations would you perform on a patient with suspected Crohn’s disease?

Answer 7

Blood: 
•FBC (⬇️ Hb, ⬆️platelets, ⬆️WCC), 
•U&E, LFTs (⬇️albumin), " 
•⬆️ESR, 
•CRP (⬆️ or may be normal), 
•haematinics to look for deficiency states: 
—ferritin, 
—Vitamin B12 
—red cell folate.

Stool microscopy and culture:
To exclude infective colitis.

AXR:
For evidence 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),
•cobblestone mucosa.

Endoscopy (OGD, colonoscopy) and biopsy:
•May help to differentiate between ulcerative colitis and Crohn’s disease,
•useful monitoring for malignancy and disease progression.
•Mucosal oedema and ulceration with ‘rose-thorn’ fissures (cobblestone mucosa), fistulae, abscesses.
•Transmural chronic inflammation with infiltration of macrophages, lymphocytes and plasma cells.
•Granulomas with epithelioid giant cells may be seen in blood vessels or lymphatics.

Radionuclide-labelled neutrophil scan:
Localization of inflammation (when other tests are contraindicated).

Question 8

How would you manage a patient with Crohn’s disease?
•Acutely
•Chronic

Answer 8

Acute exacerbation:
•Fluid resuscitation,
•IV or oral corticosteroids,
•5-ASA analogues (e.g. mesalazine, sulfasalazine) may induce a remission in colonic Crohn’s disease.
•Analgesia.
•Elemental diet may induce remission (more often used in children). •Parenteral nutrition may be necessary.
•Monitor markers of activity (fluid balance, ESR, CRP, platelets, stool frequency, Hb and albumin).
•Assess for complications.

Long term:
•Steroids: For treating acute exacerbations.
•5-ASA analogues (e.g. sulfasalazine, mesalazine): ⬇️ relapses. Useful for mild-to-moderate disease.
•Immunosuppression: Using steroid-sparing agents (e.g. azathioprine, 6-mercaptopurine, methotrexate) to ⬇️ relapses.
•Anti-TNF agents (e.g. infliximab, adalimumab): Very effective agents in achieving and maintaining remission.
—Usually reserved for refractory cases.

Advice:
•Stop smoking, dietician referral.
•Education and advice (e.g. from inflammatory bowel disease nurse specialists).

Surgery:
•Indicated for failure of medical treatment, failure to thrive in children or the presence of complications.
—This involves resection of affected bowel and stoma formation, although there is a risk of disease recurrence.

Question 9

What are the possible complications of Crohn’s disease?

Answer 9

GI: 
Haemorrhage, 
bowel strictures, 
perforation, 
fistulae (between bowel, bladder, vagina), 
perianal fistulae and abscess, 
GI carcinoma (5% risk in 10 years), 
malabsorption.

Extraintestinal features: 
Uveitis, 
episcleritis, 
gallstones, 
kidney stones, 
arthropathy, 
sacroiliitis, 
ankylosing spondylitis, 
erythema nodosum and pyoderma gangrenosum, 
amyloidosis.

Question 10

What is the prognosis for patients with Crohn’s disease?

Answer 10

Chronic relapsing condition.

Two-thirds will require surgery at some stage and two-thirds of these >1 surgical procedure.

Question 11

Give examples of possible methods of surgical management for Crohn’s disease.

Answer 11

Ileocaecal or segmental resection
—Small sections of bowel are removed with immediate re-astomosis.

A defunct ironing temporary ileostomy may help to rest the bowel in some patients with severe disease.

Stricturoplasty
—widening of obstructing strictures
—usually for recurrent colonic disease

Partial/temporary colectomy or proctolectomy
—May be required for colonic/recurrent colonic disease.

Treatment of anal complications
—eg drainage of abscesses and laying open of fistulae.