Crohn’s disease - clinical fact sheet and MCQ

Overview

Crohn’s disease (CD) is a chronic, immune-mediated inflammatory bowel disease (IBD) characterised by relapsing inflammation that can involve any segment of the gastrointestinal (GI) tract, often discontinuously. It affects all layers of the intestinal wall and is associated with systemic and extra-intestinal manifestations, such as arthropathy, pyoderma gangrenosum, erythema nodosum, uveitis, and hepatobiliary complications.

Aetiology involves genetic predisposition (up to 30% risk), with environmental triggers such as a Western diet, the patient’s gut microbiome, medications, and smoking playing significant roles.

CD is most prevalent among individuals between 15 to 25 years of age with an estimated 306 per 100,000 people affected in Australia. The incidence of CD is increasing worldwide.

Crohn’s disease diagnosis

Patients often present after years of symptoms. and up to 20% of patients with CD present initially with a complication of CD.

Common signs and symptoms include:

• fever

• abdominal pain and cramping

• diarrhoea

• weight loss

• fatigue

• anaemia

The diagnosis of Crohn’s disease requires endoscopic, histological, and radiological confirmation:

• stool microscopy and culture to exclude infective causes

• faecal calprotectin: a sensitive marker for colonic inflammation, with a high negative predictive value at a 50 µg/g cut-off; it is less reliable for proximal small bowel disease. Additional information about the use of faecal calprotectin testing in inflammatory bowel disease can be found here.

• endoscopy: detects discontinuous areas of inflammation, ulceration, mucosal oedema, erythema, with/without luminal strictures

• biopsies: show chronic inflammation and, occasionally, granulomas (not essential for diagnosis)

Other gastrointestinal inflammatory conditions or malignancies may mimic CD. The list of differential diagnoses is extensive, including:

• ulcerative colitis

• infectious colitis

• infectious enteritis and terminal ileitis

• Behcet’s disease

• irritable bowel syndrome

• coeliac disease

 Consider red flags requiring further investigation such as: 

• persistent high-grade fever (consider infection, such as from Clostridioides difficile (also known as Clostridium difficile) or Salmonella, or intra-abdominal abscess)

• abdominal distension without bowel motions or flatus (consider bowel obstruction)

• severe abdominal pain (consider an abscess or bowel obstruction due to adhesion or stricture)

• palpable abdominal mass (though may be present in CD, consider intestinal tuberculosis or malignancy)

• immunocompromising factors (consider infectious oesophagitis, enteritis, and colitis)

Management of Crohn’s disease

Management aims to induce and maintain remission, prevent complications, and improve long-term outcomes. Treatment is divided into the induction phase and maintenance phase.

1. Induction therapy:

• mild to moderate disease:

• oral prednisolone or prednisone (daily therapy until response observed, then tapering over 6–8 weeks)

• consider enteric coated oral budesonide for ileocaecal disease if corticosteroids contraindicated

• exclusive enteral nutrition may be considered for inducing remission but patient compliance may be suboptimal

• severe disease:

• intravenous corticosteroids (for 3–7 days, transitioning to oral therapy when clinical response observed)

• consider biological therapies (eg, tumor necrosis factor inhibitor, interleukin inhibitor, or anti-integrin antibody) if corticosteroids are ineffective or contraindicated 

• antibiotics are not indicated in the management of CD unless required to control infection

2. Maintenance therapy

• maintenance therapy is usually  initiated and managed by the treating gastroenterologist, though GPs play a role in managing prescriptions and monitoring progress

• prior to moving to maintenance therapy,  the gastroenterologist will ensure the patient’s condition is stable and mucosal healing evident with endoscopy

• options for maintenance therapy include:

• daily oral thiopurines (azathioprine or mercaptopurine, or if not tolerated, tioguanine)

• weekly administration of methotrexate 

• biological therapies for fistulising or luminal disease

• patients on thiopurines must be monitored frequently for complications such as hepatitis and lymphopaenia

• hepatitis, nausea, and reduced efficacy can occur due to shunting (thiopurine metabolised to 6-methyl-mercaptopurine instead of 6-tioguanine nucleotides)

• corticosteroids are ineffective and inappropriate for maintenance due to long-term side effects

• note that immunomodulatory drugs can have significant adverse effects. Patients need to be adequately screened for suitability and fully informed of risks before commencing treatment, then closely monitored for complications 

An overview of management from the Gastroenterological Society of Australia can be found here

3. Surgical interventions: 

• referral to specialist colorectal surgeon may be required for complications such as obstruction, perforation, abscess, or fistulas

4. Lifestyle interventions:

• smoking cessation significantly reduces relapse rates, risk of complications, and improves response to anti-tumor necrosis factor therapy

• encourage a diverse diet without food restriction to avoid nutritional deficiency for most patients

• in patients with intestinal strictures, a low residue (insoluble fibre) diet may minimise obstructive symptoms during disease flares

• in patients without inflammation but significant bloating, abdominal distention and pain, a low-FODMAP diet may help manage symptoms

• if an alternative diet is required, consider referral to an accredited dietitian

5. Psychological support:

• the psychological impact of CD is often underrecognised with approximately one third of patients suffering depression and/or anxiety

• in these patients, consider initiating antidepressant medication or referring for cognitive behavioural therapy

6. Crohn’s disease in pregnancy:

• active disease may cause subfertility in women 

• male fertility is unaffected by Crohn’s disease but may be impacted by certain medications (eg methotrexate)

• prior to attempting conception, women should undergo assessment with a gastroenterologist to optimise medical management and confirm disease remission to improve fertility and pregnancy outcomes

• methotrexate and allopurinol medications are contraindicated for pregnancy and/or breastfeeding, and must be modified or ceased in consultation with a gastroenterologist

References

1. Therapeutic Guidelines. Crohn disease in adults. 2022. Available at: https://app.tg.org.au/viewTopic?etgAccess=true&guidelinePage=Gastrointestinal&topicfile=c_GIG_Gastro-oesophageal-reflux-in-adultstopic_1&guidelinename=auto&sectionId=c_GIG_Crohn-disease-in-adultstopic_16#c_GIG_Crohn-disease-in-adultstopic_16. (last viewed January 2025). 

2. Cushing K, Higgins PDR. Management of Crohn Disease: A Review. JAMA. 2021 5;325(1):69-80. doi: 10.1001/jama.2020.18936. 

3. Busingye D, Pollack A, Chidwick K. Prevalence of inflammatory bowel disease in the Australian general practice population: A cross-sectional study. PLoS One. 2021;16(5):e0252458. doi: 10.1371/journal.pone.0252458.

4. Ranasinghe IR, Tian C, Hsu R. Crohn Disease. [Updated 2024 Feb 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025. Available from: https://www.ncbi.nlm.nih.gov/books/NBK436021/. (last viewed January 2025)

5. Gastroenterological Society of Australia. Pregnancy, Fertility, and Inflammatory Bowel Disease. 2018. Available at: https://www.gesa.org.au/public/13/files/Education%20%26%20Resources/Clinical%20Practice%20Resources/IBD%20in%20Pregnancy/IBD_Pregnancy_Fertility_GP_Obstetrician_Factsheet.pdf. (last viewed February 2025). 

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