Crohn disease (CD) is a disorder of unknown etiology characterized by transmural inflammation of the gastrointestinal tract.
Common presenting symptoms include chronic diarrhea, 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 extraintestinal involvement, intestinal obstruction, abscess formation, sinuses, and fistulae.
CD is a disorder of unknown etiology characterized 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 characterized 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
- abdominal pain
- prolonged diarrhea
- perianal lesions
Other diagnostic factors
- bowel obstruction
- blood in stools
- abdominal tenderness
- weight loss
- oral lesions
- abdominal mass
- extraintestinal 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 fiber
- diet high in ultra-processed foods
- oral contraceptives
- not breastfed
- nonsteroidal 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
- fecal calprotectin or fecal lactoferrin
- serologic markers
ileocecal disease not fistulizing with <100 cm of bowel affected: initial presentation or relapse
colonic disease not fistulizing: initial presentation or relapse
extensive small bowel disease (>100 cm of bowel affected) not fistulizing: initial presentation or relapse
upper gastrointestinal disease (esophageal and/or gastroduodenal disease) not fistulizing: initial presentation or relapse
perianal or fistulizing disease: initial presentation or relapse
- Ulcerative colitis (UC)
- Infectious colitis
- Pseudomembranous colitis
- Adverse events associated with EGD and EGD-related techniques
- Clinical practice guidelines for the management of anorectal abscess, fistula-in-ano, and rectovaginal fistula
Crohn disease: what is it?
Crohn disease: what treatments work?More Patient leaflets
- Log in or subscribe to access all of BMJ Best Practice
Use of this content is subject to our disclaimer