Crohn's Disease

see also: Acute flare of Crohn's disease


  • Chronic diarrhoea
  • Weight loss
  • Right lower quadrant abdominal pain mimicking acute appendicitis
  • Fatigue
  • Bowel obstruction manifesting as bloating, distension, cramping abdominal pains, borborygmi, vomiting, constipation
  • Fever
  • Mucus, blood, and pus in the stool


Stool frequency and consistency
Rectal bleeding
Abdominal pain
Malaise, fever and weight loss
Symptoms of extraintestinal (joint, cutaneous and eye) manifestations of IBD
Is the patient on allopurinol (affects dose of azathioprine)
White ethnicity
Family history of Crohn's disease
Age 15 to 40 years or 60 to 80 years
Drug history: NSAIDs, recent antibiotic use
Recent travel


  • Peri-anal lesions e.g skin tags, fistulae, abscesses, scarring
  • Inflammatory lesions of the oral cavity,

Laboratory investigations

Faecal calprotectin

  • To support clinicians differentiate between differential diagnoses of IBD and IBS if cancer is not suspected

FBC to detect anaemia
Vitamin B12 and folate (disease in small intestine affecting absorption)
Thiopurine methyltransferase (TPMT) prior to starting azathioprine
Comprehensive metabolic panel (CMP) to detect for severe or chronic disease
Elevated ESR/CRP
Stool testing to eliminate C.Diff especially after recent antibiotic use and other parasitic

Radiological investigations

Colonoscopy with biopsy
Inflammatory lesions in the pylorus or duodenum, small bowel or anus
Discontinuous disease distribution/skip lesions (areas of abnormal mucosa separated by normal mucosa)
Biopsy will confirm histological diagnosis

CT scan

  • Skip lesions
  • Bowel wall thickening
  • Surrounding inflammation
  • Abscesses
  • Fistulae

MRI to stage disease activity


First line

Smoking cessation

Monotherapy (anti-inflammatory drugs)

  • Conventional glucocorticoids for people presenting for the first time or have had a single flare up in the last 12 months
  • prednisolone, methylprednisolone or intravenous hydrocortisone
  • Consider budesonide for patients presenting for the first time with distal ileal, ileocaecal or right‑sided colonic disease and cannot tolerate glucocorticoid treatment
  • 5‑aminosalicylate (mesalazine) if glucocorticoids are contraindicated or cannot be tolerated
  • Do not offer azathioprine, mercaptopurine or methotrexate as monotherapy to induce remission

Add-on therapy

  • Azathioprine or mercaptopurine (immunosuppresants)
  • Indicated in patients with two or more inflammatory exacerbations in a 12‑month period
  • Note: Measure levels of TPMT (thiopurine S-methyltransferase) before administering azathioprine or mercaptopurine - do not offer these medications of TPMT is low or deficient due to the risk of developing severe side-effects
  • Consider methotrexate as an add-on therapy if patients cannot tolerate azathioprine or mercaptopurine or if TPMT levels are low

Second line

TNF inhibitors (biologic immunosuppresants)

  • Infliximab and adalimumab
  • Recommended as treatment options for adults with severe active Crohn's disease who have not responded to conventional therapy (including other immunosuppressive or corticosteroid tre


Surgical options

  • Consider surgery as an alternative to medical treatment early in the course of the disease for people whose disease is limited to the distal ileum
  • Consider balloon dilation and surgical interventions for patients with strictures

Prior to discharge

Follow up

Review patients with uncomplicated cases of Crohn's every 6 months
Review patients using azathioprine or mercaptopurine every 3 months
Monitor FBC, renal function and LFTs throughout treatment with immunosuppressants
DEXA scans due to increased risk of osteoporosis


Consider antibiotics if sepsis is suspected
Intestinal Obstruction
Extra Intestinal complications

  • arthropathy
  • liver abscess
  • Primary sclerosing cholangitis
  • ocular (uveitis, iritis, and episcleritis) and cutaneous (erythema nodosum) manifestations

methotrexate associated hepatotoxicity, pulmonary fibrosis or myelosuppression


Lifelong condition, with periods of active disease alternating with periods of remission


  • Transmural inflammation (fissuring ulcer, abscess, or fistula)
  • Lymphoid aggregates
  • Non-caseating granuloma
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