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Inflammatory bowel disease rates are rising, but there are many similar conditions that clinicians must consider before making a diagnosis.
Inflammatory bowel disease (IBD) affects over 80 000 people in Australia, which has one of the highest rates of IBD in the world.
The numbers of IBD — which comprises Crohn’s disease and ulcerative colitis — are rising globally, and are expected to affect 1% of the population by 2030.
Early diagnosis and treatment are vital for reducing the risk of long term complications, but there are many other conditions that mimic the symptoms of IBD that need to be considered when making a diagnosis.
In a perspective published in the Medical Journal of Australia, researchers from Alfred Health and Monash University, Melbourne, have outlined a range of differential diagnoses for clinicians to be aware of when a patient presents with intestinal inflammation:
Non-steroidal anti-inflammatory drug enteropathy
Non-steroidal anti-inflammatory drugs (NSAIDs) are frequently implicated in small bowel injury, both with short and long term use. Because the endoscopic and histologic features of NSAID enteropathy may appear similar to Crohn’s disease features, it’s important to take a detailed drug history when assessing the patient.
Infectious colitis
Infectious colitis commonly includes vomiting and fever along with bowel symptoms. It can be diagnosed with a stool culture in up to 50% of cases, and usually resolves spontaneously. Taking a detailed travel history and asking about any unwell people the patient has been in contact with is advised.
Microscopic colitis
Microscopic colitis is a common cause of chronic diarrhoea in women and older people. It can be associated with medications such as NSAIDs, anti-depressants and anti-Parkinsonian drugs. It may not show up on a colonoscopy, but histology may reveal inflammatory infiltrate of subepithelial collagen or intra-epithelial lymphocytes.
Ischaemic colitis
Ischaemic colitis occurs when there is insufficient blood supply to the colon, causing mucosal injury. It usually affects the left colon and can appear as a circular target sign on computed tomography (CT) scan or as a single ulcer on endoscopy. Clinicians should consider the possibility of ischaemic colitis when there are vascular risk factors.
Segmental colitis associated with diverticulosis
If the endoscopic and histologic findings look like IBD, but there is rectal sparing, it could be a case of segmental colitis associated with diverticulosis, which affects the sigmoid and causes colonic inflammation of the surrounding areas of diverticula.
Vasculitides
Behcet’s syndrome, a form of vasculitis, can cause ileocaecal ulcerations similar to Crohn’s disease. It typically affects people from eastern Asia and the Mediterranean and can co-occur with ocular disease, genital ulceration and pathergy. CT or magnetic resonance imaging scans can assist in distinguishing vasculitis from IBD.
Tuberculosis
It can be difficult to differentiate gastrointestinal tuberculosis (GITB) from Crohn’s disease as they both affect the ileum and have a similar presentation, but the correct diagnosis is crucial in these cases to avoid significant consequences from incorrect treatment. GITB often has a shorter duration of disease and is accompanied by fever and an abdominal mass. Necrotic lymph nodes on imaging are another indicator, although endoscopic and microbiological assessment will be crucial in confirming the diagnosis.
Lymphogranuloma venereum
Lymphogranuloma venereum is a sexually transmitted disease caused by Chlamydia trachomatis. Patients may present with proctitis, rectal discharge, tenesmus and altered bowel habits. It can be diagnosed with rectal swabs and treated with antibiotics, and is most likely to affect men who have sex with men or people with human immunodeficiency virus (HIV), hence taking a detailed sexual history is crucial.
Chemical colitis
Chemical colitis can occur from intentional rectal administration of various chemicals, such as alcohol or detergents. Symptoms usually resolve with conservative treatment except for severe cases, which may require surgical resection.
For more information, read the perspective in the Medical Journal of Australia.
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