Crohn's disease (CD) is a disorder of unknown aetiology characterised by transmural inflammation of the gastrointestinal tract.
Common presenting symptoms include chronic diarrhoea, weight loss, and right lower quadrant abdominal pain mimicking acute appendicitis.
Diagnosis confirmed by colonoscopy with ileoscopy and tissue biopsy.
Specialist input is required from the time of diagnosis, as treatment regimens require frequent monitoring of clinical response, knowledge of common adverse events, and expertise in managing potentially serious adverse events.
The overall treatment goals are to induce and maintain remission, and to prevent relapse or recurrence.
Complications include extra-intestinal involvement, intestinal obstruction, abscess formation, sinuses, and fistulae.
CD is a disorder of unknown aetiology characterised by transmural inflammation of the gastrointestinal (GI) tract. CD may involve any or all parts of the entire GI tract from mouth to perianal area, although it is usually seen in the terminal ileal and perianal locations. Unlike ulcerative colitis, CD is characterised by skip lesions (where normal bowel mucosa is found between diseased areas). The transmural inflammation often leads to fibrosis causing intestinal obstruction. The inflammation can also result in sinus tracts that burrow through and penetrate the serosa, thereafter giving rise to perforations and fistulae.
History and exam
Key diagnostic factors
- presence of risk factors
- abdominal pain
- prolonged diarrhoea
- perianal lesions
Other diagnostic factors
- bowel obstruction
- blood in stools
- abdominal tenderness
- weight loss
- oral lesions
- abdominal mass
- extra-intestinal manifestations (e.g., erythema nodosum or pyoderma gangrenosum)
- white ethnicity and Ashkenazi Jewish ancestry
- age 15-40 or 50-60 years
- family history of CD
- cigarette smoking
- diet high in refined sugar
- diet low in fibre
- diet high in ultra-processed foods
- oral contraceptive pill
- not breastfed
- non-steroidal anti-inflammatory drugs (NSAIDs)
1st investigations to order
- iron studies (serum iron, serum ferritin, total iron binding capacity [TIBC], transferrin saturation)
- serum vitamin B12
- serum folate
- comprehensive metabolic panel (CMP)
- C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
- stool testing
- Yersinia enterocolitica serology
- plain abdominal x-ray
- MRI abdomen/pelvis
- CT abdomen
Investigations to consider
- abdominal and pelvic ultrasonography
- tissue biopsy
- wireless capsule endoscopy
- faecal calprotectin or faecal lactoferrin
- serological markers
ileocaecal disease not fistulating with <100 cm of bowel affected: initial presentation or relapse
colonic disease not fistulating: initial presentation or relapse
extensive small bowel disease (>100 cm of bowel affected) not fistulating: initial presentation or relapse
upper gastrointestinal disease (oesophageal and/or gastroduodenal disease) not fistulating: initial presentation or relapse
perianal or fistulating disease: initial presentation or relapse
- Ulcerative colitis (UC)
- Infectious colitis
- Pseudomembranous colitis
- Informed consent for GI endoscopic procedures
- Colorectal cancer prevention: colonoscopic surveillance in adults with ulcerative colitis, Crohn's disease or adenomas
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