Inflammatory bowel disease

Question 1

What is ulcerative colitis and where does it affect?

Answer 1

• UC is a relapsing + remitting inflammatory disorder of colonic mucosa
• may affect:
  
  • just the rectum (proctitis ~30%)
  • extend to involve part of colon (left-sided colitis, in ~40%)
  • entire colon (pancolitis, in ~30%)
• ‘never’ spreads proximal to ileocaecal valve (except for backwash ileus)

Question 2

What are the main risk factors for UC?

Answer 2

• FHx of IBD → between 10-20% of pts have at least 1 family member w/ IBD
• HLA-B27 → identified in most pts w/ UC
• Infection → up to 50% of relapses of colitis are associated w/ enteritis due to recognised pathogens

Question 3

What are the clinical features of UC?

Answer 3

• Acute attacks alternate w/ asymptomatic intervals
• Chronically active course (>2 relapses/year)
• Incomplete remission despite adequate treatment
• Diarrhoea w/ macroscopic visible blood + mucus
• Abdominal pain, tenesmus
• Tenderness (left lower abdo)
• Extra-intestinal → anaemia, fever, weight loss, malaise, arthritis, sacroilitis, erythema nodosum, pyoderma gangraenosum, eye symptoms
• Concomitant disease → PSC, amyloidosis, liver disease, ank spond

Question 4

What is the pathophysiology of UC?

Answer 4

• microscopically, UC usually involves ONLY THE MUCOSA
• formation of crypt abscesses
• coexisting depletion of goblet cell mucin
• ulcerated areas soon covered by granulation tissue
• undermining mucosa of XS of granulation tissue form polypoidal mucosal excrescences known as polyps or pseudopolyps

Question 5

What are the investigations for UC?

Answer 5

• Stool studies → faecal calprotectin
• Bloods → FBC, LFTs, ESR, CRP
• AXR → toxic megacolon
• Flexi sigmoidoscopy
• Colonoscopy + biopsies → widespread ulceration with preservation of adjacent mucosa which has appearance of polyps

Question 6

How do you assess severity of a UC attack?

Answer 6

Question 7

What is the management of UC?

Answer 7

• Mild attack → mesalazine (5-ASA) for remission-induction/maintenance; given PR for distal disease or PO For extensive disease, combine PO + PR if flare
• Moderate attack → if 4-6 motions/day but otherwise well, induce remission w/ oral prednisolone 40mg/d for 1 wk, then taper by 5mg/week over 7 weeks → then maintain on 5-ASA
• Severe attack → admit for: IV hydration/electrolyte replacement; IV steroids (hydrocortisone or methylprednisolone); rectal steroids (hydrocortisone); thromboembolism prophylaxis

Question 8

What are the complications of UC?

Answer 8

• Toxic megacolon → colon begins to widen (dilate), may be due to problems with muscle contraction or digestive reflexes; rare complication + occurs in 2.5% of those with UC
• Colonic adenocarcinoma → develops in 3-5% pts w/ UC; risk increases with duration of disease

Question 9

What is Crohn’s disease?

Answer 9

• chronic inflammatory disease
• characterised by transmural granulomatous inflammation
• affecting any part of gut from mouth to anus (esp term ileum 70%)
• unlike UC, there is unaffected bowel between areas of active disease (skip lesions)
• age 15-40 or 60-80yrs → bimodal age distribution for onset

Question 10

What are the clinical features of Crohn’s disease?

Answer 10

• diarrhoea → usually non-bloody
• weight loss → Crohn’s > UC
• systemic features → fatigue, fever, malaise, anorexia
• abdo tenderness/mass → RIF
• perianal abscess/fistulae/skin tags
• mouth ulcers
• clubbing

Question 11

What is the pathophysiology of Crohn’s?

Answer 11

• initial lesion starts as an inflammatory infiltrate around intestinal crypts
• subsequently develops into ulceration of the superficial mucosa
• inflammation progresses to involve deeper layers + forms non-caseating granulomas
• granulomas involve ALL layers of intestinal wall + mesentry + regional lymph nodes
• finding of these granulomas is highly suggestive of CD, yet absence does not exclude diagnosis

Question 12

What investigations are done for Crohn’s?

Answer 12

• stool MC+S → faecal calprotectin
• bloods → FBC, iron studies, B12, folate, CRP, ESR
• colonscopy + biopsy → cobble-stone appearance, histology to diagnose
• CT/MRI → localises disease + diagnoses complications

Question 13

What is the management of Crohn’s in terms of inducing remission?

Answer 13

• conventional steroids (prednisolone, methylpred, IV hydrocortisone) to induce remission in people w/ a 1^st presentation or single inflammatory exacerbation of CD in a 12 month period
• in ppl w/ 1+ of distal ileal, ileocaecal or right-sided colonic disease who decline, cannot tolerate or in whom a conventional steroid is contraindicated → consider budesonide
• consider adding azathioprine or mercaptopurine to conventional steroid or budesonide to induce remission in CD if:
  
  • 2+ inflammatory exacerbations in a 12-month period, OR
  • steroid dose cannot be tapered

Question 14

What is the management of Crohn’s in terms of maintaining remission?

Answer 14

• offer azathioprine or mercaptopurine as monotherapy to maintain remission
• consider methotrexate to maintain remission only in people who
  
  • needed methotrexate to induce remission, OR
  • have tried but did not tolerate azathioprine or mercaptopurine

Question 15

What are complications of Crohn’s?

Answer 15

• intestinal obstruction → due to bowel wall thickening - presents w/ abdo pain, N+V, abdo distension + dilated bowel loops on AXR
• malignancy → overall inc risk of cancer + inc risk of colon adenocarcinoma
• kidney stones → develops in pt w/ severe disease due to inc absorption of oxalate, poor digestion of fats, acidosis + dehydration

Question 16

Summary of differences between UC + CD?

Answer 16