Inflammatory Bowel Disease

Inflammatory Bowel Disease


Overview Inflammatory bowel disease is a common condition. It is divided into two types: Crohn disease and Ulcerative colitis. Both these condition differ in pathology, progression and complication, but they do share a lot similar characteristics as well.

Colitis: Inflammation of the colon, which may be due to infectious, autoimmune, ischemic, or idiopathic causes.
Inflammatory Bowel Disease: Autoimmune-mediated intestinal inflammation primarily due to either Crohn disease or ulcerative colitis.


Ulcerative Colitis   Crohn’s Disease
Both Gender Male<Female
2-19/100,000 Incidence (per year) 21-20/100,000
15-40yo Onset 15-40yo
Distal colon Location Dital ileum and caecum
Continuous superficial inflammatory lesion Pathology Discontinuous, patchy transmural inflammatory skip lesions
Severe bleeding, toxic megacolon, perforation, colon cancer Complications Stenosis, abcess formation, fistula, strictures, colon cancer 
Histological Difference between Crohn Disease and Ulcerative Colitis

Risk Factors

Risk Factors
Ulcerative Colitis Crohn's Disease
Family history of inflammatory bowel disease White ancestry
HLA-B27 Family history
Infection  High sugar diet
NSAIDs  Oral contraceptive pill, NSAIDs
Not smoking or former smoker Cigarette smoking
Not breastfed

Signs and Symptoms

Proctitis (50%) Left-sided colitis (30%) Pancolitis (∼20%)
Area affected Inflammation of the rectum Inflammation from rectum up to the splenic flexure Inflammation of the entire colon
Rectum and deification Rectum always involved. Symptoms of urgency and frequency due to rectal irritablity. Rectal irritation
Stool Blood mucus mixed with loose stools (frank bloody diarrhea rare) Bblood mucus in stools, often leading to diarrhea Diarrhea
Side note Ulcerative colitis typically presents in young adults with relapsing bloody diarrhoea, malaise, fever and weight loss. Crohn's can have similar presentation or have a more insidious onset with other complications such as malabsorption and pain.

Extra-intestinal Manifestations 

  • Both UC and CD
    • Uveitis (Iritis/conjuctivitis)
    • Mouth ulcer
    • Large joint arthritis
    • Skin Rash (Erythema nodosum and/or Pyoderma gangrenosum)
    • Anaemia
  • Ulcerative Colitis
    • Liver disease: Primary sclerosing cholangitis, Cirrhosis, Amyloidosis
  • Crohn Disease
    • Renal disease: stones and amyloidosis
    • Gallstones
    • Osteomalacia
General clinical features of BD

Differential Diagnosis

The differential diagnosis of inflammatory bowel disease includes other causes of chronic diarrhoea

Remember Infection must be excluded, and it is necessary to check for infections with organisms such as Entamoeba histolytica, Salmonella, Shigella, E coli, and Campylobacter, as well as Clostridium difficile, which can occur in the absence of prior antibiotic exposure.

Causes of Colitis (inflammation of the colon)

  • Inflammatory Bowel Disease
  • Infection
  • Radiation
  • Ischaemic colitis
  • Diversion colitis
  • Toxic exposure (chemicals)
  • Lymphocytic colitis
  • Collagenous colitis
Differential Diagnosis of IBD (Image adapted from Netter Images)



  • Stool culture - to rule out C. difficle colitis
  • FBC - increase WCC, decrease Hb
  • ESR/CRP - increased
  • Serum folate
  • Serum vitamin B12
  • Abdominal X-ray - may show oedematous colonic mucosa (thumbprinting)

Specific for Ulcerative Colitis

  • Colonoscopy – sigmoidoscopy usually shows erythematous, grandular, or frankly ulcerated rectal mucosa with mucus and blood
  • Biopsy - check severity and to Exclude Crohn's disease
  • Serological markers – ANCA (70% of patients with UC have this)
  • Serological marker – ASCA (70% of patients with Crohn’s have this)

Specific for Crohn's Disease

  • Double-contrast barium enema (rarely used) - in subacute/chronic presentations to show mucosal irregularity and narrowing.
  • CT - may show an inflammatory mass, abscess formation, localised or free perforation
  • MRI - for anal disease
  • Biopsy - check severity and confirm Crohn's disease


  • Presence of chronic diarrhea for more than four weeks and evidence of active inflammation on endoscopy and chronic changes on biopsy.
  • Eliminate differentials with:
    • History - risk factors
    • Laboratory studies - stool culture for bacteria (C. difficile, Salmonella, Shigella, Campylobacter, Yersinia)
    • Endoscopy - continuos inflammatory lesion beginning mainly from the distal colon
Investigation In subacute or chronic presentations, small muscusal disease may be shown by a small bowel contrast study (shows mucosal irregularity and narrowing) or a white cell scan showing ileal 'hot spots'


Ulcerative Colitis Crohn's Disease
Superficial inflammation. Disease present in the distal colon and rectum and spread proximally with increasing extend of disease. Transmural inflammation. Disease commonly focused in the terminal ileum and caecum, but may affect the anus, colon, or entire small bowel.
Acute neutrophil infiltration in the mucosa and submucosa Lymphoid aggregates, particularly in the subserosal tissues (Crohn's rosary).
Mucosal crypt abscess with goblet cell mucin depletion Mucosal crypt ulceration, and fissuring ulceration.
More severe inflammation, there can be aphthous ulcers, granulation tissue -> pseudopolyps Mucosal thickening and cobblestone.
Chronic 'burnt out' disease leads to a pale, featureless, ahaustral pattern to the colon. Transmural inflammation may occur in sever cases. Extensive fibrosis and muscle hyperplasisa may occur, giving rise to stenosis. Perforation, fistulation, and abscess formation are occasional sequelae of transmural inflammation.
Gross Pathological changes in IBD


The management differs for UC and CD. CD is more severe and encounters more complications. The principles of medical treatment is to reduce inflammation and prevent complications.


  • Close monitoring - bloods
  • Acute derangement in blood results should be corrected  (ie. blood transfusion for severe anaemia, potassium supplementation, nutrition support).
  • Diet modification
  • Medical treatment
    • Steroids (suppository or systemic)
    • 5-ASA
    • Oral immunosuppresives (methotrexate, azathiopurine)
    • Immunomodulators (anti-TNFa)
    • Antibiotcs
  • Surgical treatment
    • Ulcerative colitis - indicated for acute colitis that fails to respond to treatment and for chronic colitis
    • Crohn's disease - deal with septic complications, relieve significant bowel obstruction, and remove as little bowel as possible.
Ulcerative Colitis Medical and Surgical Treatment
Proctitis (50%) Left-sided colitis (30%) Pancolitis (~20%)
Topical steroids (suppsoitories or foam enema) + + +
5-ASA + + +
Systemic Steroids (prednisalone) - -/+ +
Oral immunosuppressives (azathiopurine)  -  - +
Immunomodulators (anti-TNFa) - - +
Surgery is indicated for acute colitis that fails to respond to treatment and for chronic colitis. Surgical treatment include removing parts of bowel or entire colon.


Crohn's Disease Medical and Surgical Treatment
Medical Treatment Surgical Treatment
5-ASA Acute: Free perforation, sever haemorrhage, acute severe colitis, complete intestinal obstruction
Systemic steroids (hydrocortisone, prednisolone) Subacute: Inflammatory mass, subacute obstruction, abscess formation, symptomatic fistulation
Immunosuppressives (azanthiopurine, methotrexate) Chronic: Steroid dependency or complications, cancer treatment
Immunomodulators (anti-TNFa)
Dietary modification

Complications and Progns

Local Complications

  • Ulcerative Colitis
    • Toxic Megacolon
    • Perforation
    • Massive haemorrhage
    • Strictures
    • Carcinoma of the colon
  • Crohn Disease
    • Anorectal Disease
    • Obstruction
    • Fistula
    • Carcinoma of the colon

Extra-intestinal Manifestations 

  • Both UC and CD
    • Uveitis (Iritis/conjuctivitis)
    • Mouth ulcer
    • Large joint arthritis
    • Skin Rash (Erythema nodosum and/or Pyoderma gangrenosum)
    • Anaemia
  • Ulcerative Colitis
    • Liver disease: Primary sclerosing cholangitis, Cirrhosis, Amyloidosis
  • Crohn Disease
    • Renal disease: stones and amyloidosis
    • Gallstones
    • Osteomalacia
Think Because of transmural inflammation, Crohn disease often is complicated by fistula formation.
Ulcerative Colitis Complications


Ulcerative Colitis

  • Surgery can be curative

Crohn's Disease

  • Recurrence of the disease after resection occurs in some 50% of cases within 10 years


Best Practice
Oxford Handbook of Clinical Surgery
Oxford Handbook of Emergency Medicine
Oxford Handbook of Clinical Medicine