How to assess for Crohn's disease (Crohn's)

From the Guidelines

Assessing for Crohn's disease requires a comprehensive approach combining clinical evaluation, laboratory tests, imaging, and endoscopic procedures, with the most recent evidence suggesting that a combination of these methods is necessary for accurate diagnosis and management 1. To assess for Crohn's disease, the following steps should be taken:

• Begin with a thorough medical history focusing on symptoms like persistent diarrhea, abdominal pain, weight loss, fatigue, and family history of inflammatory bowel disease.
• Physical examination should assess for abdominal tenderness, masses, perianal disease, and extraintestinal manifestations.
• Laboratory tests should include complete blood count to check for anemia and elevated white blood cells, inflammatory markers (C-reactive protein, erythrocyte sedimentation rate), fecal calprotectin, and tests to exclude infectious causes.
• Imaging studies like CT enterography or MR enterography can visualize the small bowel and identify wall thickening, strictures, or fistulas, with the most recent consensus recommendations suggesting that these imaging modalities be used to evaluate and interpret small bowel Crohn's disease 1.
• The gold standard for diagnosis is ileocolonoscopy with biopsies, which allows direct visualization of the colon and terminal ileum to identify characteristic findings like skip lesions, cobblestoning, and ulcerations, and should be performed in all patients with symptoms suggestive of IBD to enable diagnosis and assess the location, extent, and severity of mucosal lesions 1.
• Upper endoscopy may be performed if upper GI symptoms are present, and capsule endoscopy can be useful for examining small bowel areas not accessible by standard endoscopy.
• Histological examination of biopsies typically shows non-caseating granulomas, transmural inflammation, and architectural distortion. This multi-modal approach is necessary because no single test can definitively diagnose Crohn's disease, and the condition must be distinguished from other disorders like ulcerative colitis, irritable bowel syndrome, and infectious colitis. Some key points to consider when assessing for Crohn's disease include:
• The use of standardized tools for symptom assessment, such as the Harvey-Bradshaw Index (HBI), to allow for greater objective and valid assessment 1.
• The importance of cross-sectional imaging in all patients at diagnosis to assess the extent and severity of disease 1.
• The need for careful evaluation of disease characteristics at baseline to inform differential diagnosis, establish the extent, severity, and behavior of disease, and objectively evaluate inflammation and rule out complications 1.

From the Research

Assessing Crohn's Disease

To assess Crohn's disease, several methods can be employed, including:

• Laboratory tests, such as erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and complete blood count (CBC) 2, 3, 4
• Imaging modalities, including colonoscopy, radiography, and other techniques to evaluate intestinal and extraintestinal involvement 5
• Clinical assessment, using tools such as the Crohn's Disease Activity Index (CDAI) 2

Laboratory Parameters

The following laboratory parameters have been found to be useful in assessing Crohn's disease activity:

• CRP: shown to have a statistical significance in relation to disease activity 2, 3
• ESR: higher in Crohn's disease than in ulcerative colitis, but does not closely reflect disease activity in individual patients 3
• Red cell distribution width (RDW): elevated in patients with active Crohn's disease, and may be a useful marker for assessing disease activity 4
• Haemoglobin, hematocrit, and platelet count: also found to be reliable indicators of disease activity 2

Imaging Techniques

Imaging modalities play a crucial role in evaluating Crohn's disease, providing information on intestinal and extraintestinal involvement. The choice of imaging technique depends on the specific clinical question and the strengths and limitations of each modality 5.

Disease Activity Assessment

Assessing disease activity in Crohn's disease is crucial for effective management. A combination of laboratory parameters, clinical assessment, and imaging modalities can provide a comprehensive evaluation of disease activity 2, 6, 5.