Crohn's Disease

Question 1

Definition

Answer 1

• chronic inflammatory process affecting GIT (lips to anal margin)
• slightly more common in women
• 25-40 years old, second peak: 70 year old
• common at ileal

Question 2

Aetiology

Answer 2

• genetic and environmental factor

Genetic

• first degree relative
• monozygotic twins

Environmental factor
- smoking increase risk by threefold

Question 3

Pathogenesis

Answer 3

• increased permeability of mucous membrane (genetically determined)
• increased passage of luminal antigens–> cell mediated inflammatory response–> release of proinflammatory cytokine
• defect in suppressor T cell–> escalation of inflammatory response
• local and systemic inflammatory response

Question 4

Pathology

Answer 4

Macroscopically

• fibrotic thickening of intestinal wall with narrow lumen
• dilated bowel proximal to stricture
• deep mucosal ulceration in stricture
• oedema in mucosa between ulcer: cobblestone appearance
• transmural inflammation–> adhesion, inflammatory masses with mesenteric abscess and fistula
• mesenteric lymph node enlarged
• skip lesion

Microscopically

• focal area of inflammation involving all layers of intestinal wall
• non caseating granuloma
• multifocal arterial occlusion in muscularis propria
• deep fissuring ulceration
• may have completely normal area next to area of severe inflammation

Question 5

Clinical feature

Answer 5

Acute

• resemble acute appendicitis
• diarrhoea preceding attack

Chronic

• history of mild diarrhoea extending over many months a/w intestinal colic
• pain in RIF
• tender mass palpable
• intermittent fever, secondary anaemia and weight loss
• perianal abscess or fissure
• intestinal obstruction
• children before puberty may have retarded growth and sexual development
• fistulation to adjacent structure

Extra-intestinal manifestation

• erythema nodosum
• pyoderma gangrenosum
• arthropathy
• iritis/ uveitis
• aphthous ulceration
• amyloidosis
• gallstone
• renal calculi
• primary sclerosing cholangitis
• chronic active hepatitis
• sacroilitis

Question 6

Investigation

Answer 6

• FBC: exclude anaemia
• reduced level of albumin, magnesium and zinc
• CRP
• endoscopy: inflamed mucosa, ulcer and stricture
• USS: inflamed, thickened bowel loop, fluid collection and abscess
• barium enema: stricture and prestenotic dilatation
• MRI: assess complex perianal disease
• CT scan: fistula, intra-abdominal abscess, bowel thickening/ dilatation
• MR enteroclysis: small bowel stricturing
• fistulography: demonstrate anatomy and complexity of fistula and allow adequate planning for surgery

Question 7

Medical therapy

Answer 7

• steroid**: induce remission, short course, topical to reduce systemic SE
• antibiotic (metronidazole and ciprofloxacin): evidence of mass/ abscess (drainage +- resection)
• immunomodulatory (azathioprine, 6-metacaptopurine, cyclosporin): inhibit cell mediated immune response
• monoclonal antibody (infliximab, adalimumab): target TNF-alpha, effective tx of fistula (perianal disease) but cessation of therapy a/w high risk of reactivation of fistulae
• nutritional support (nasoenteric or IV feeding)

Question 8

Surgery

Answer 8

• ileocaecal resection
• segmental resection
• colectomy and ileorectal anastomosis
• subtotal colectomy and ileostomy
• temporary loop ileostomy
• proctocolectomy
• strictureplasty

Question 9

Complication

Answer 9

• recurrent IO
• bleeding
• perforation
• failure of medical therapy
• intestinal fistula
• fulminant colitis
• malignant change
• perianal disease