Colonoscopy is the first-line approach for assessing ongoing disease activity in inflammatory bowel disease. Biopsy samples are obtained from the ileum, right colon, left colon, and rectum, even if endoscopically normal in appearance, to assess for histologic evidence of inflammation; biopsy samples of uninvolved mucosa are recommended to measure the extent of histologic disease. Typical findings in patients with Crohn disease include focal (discontinuous) chronic inflammation, focal crypt irregularity (discontinuous crypt distortion), granulomas, and transmural lymphoid aggregates.
A complementary noninvasive approach is MR enterography, which can be particularly useful in younger patients with Crohn disease; if this technique is not available, CT enterography can be considered. Compared with other imaging modalities, MR enterography provides contrast-enhanced tissue evaluation with optimal detection of fluid and submucosal edema, multiplanar capability, multiparametric assessment, and functional information without exposure to ionizing radiation.
MR enterography is more effective than ultrasound in assessing the entire gastrointestinal tract and the perianal region. The sensitivity of ultrasound is also operator-dependent; however, because it lacks radiation exposure, ultrasound (and MRI) are often preferred to CT, especially in younger patients.
Barium contrast studies are less commonly used now that detailed CT, MRI, and capsule endoscopy techniques are available to assess for small-bowel and pelvic Crohn disease.
Though currently not in widespread use outside of research studies, fecal calprotectin represents a future tool in the differentiation of inflammatory bowel disease from irritable bowel syndrome and in following patient disease activity.
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Cite this: Charles Bernstein. Skill Checkup: A 28-Year-Old Man With Diarrhea, Nausea, Vomiting, and Abdominal Cramping - Medscape - Feb 01, 2022.