Diagnosis

There is no single gold standard method for the diagnosis of Crohn’s disease. Diagnosis is based on clinical evaluation and a combination of endoscopic, radiological and pathological evidence of the disease (1).

• history and examination
  • careful history of chronic, remitting disease - the problems may take months or years to clinically manifest,
  • inquire about onset of symptoms, recent travel, food intolerance, medication (e.g. NSAIDs), history of appendectomy
  • look for any risk factors e.g. –smoking, family history, recent infectious gastroenteritis
  • features of any extraintestinal manifestations - in mouth, skin, eye, joints (1)
• initial laboratory investigations
  • full blood count
  • CRP or ESR
  • urea and electrolytes (2)
  • liver function test (including albumin) (3)
  • faecal calprotectin – to identify gut inflammation
  • microbiological testing - for infectious diarrhoea (including Clostridium difficile toxin) (1)
• other investigation methods used include
  • plain abdominal x-ray
  • barium studies of small and large bowel showing narrowing - Kantor's string sign of the terminal ileum - and skip lesions
  • sigmoidoscopy and rectal biopsy
  • colonoscopy with multiple biopsy (1,2).

Crohn's disease confined to the colon may be difficult to discriminate from ulcerative colitis. Features that may help discriminate the two conditions are described under 'diagnosis of ulcerative colitis'.

Reference:

• (1) Van Assche G et al. The second European evidence-based consensus on the diagnosis and management of Crohn's disease: Definitions and diagnosis. Journal of Crohn's and Colitis 2010; 4:7–27
• (2) Carter MJ et al. Guidelines for the management of inflammatory bowel disease in adults. Gut. 2004;53 Suppl 5:V1-16
• (3) British Society of Paediatrics Gastroenterology Hepatology and Nutrition (BSPGHAN) 2008. Guidelines for the Management of Inflammatory Bowel Disease (IBD) in Children in the United Kingdom