Case 7 Discussion

Learning Objectives:

  1. Perform an appropriate initial work-up for a patient with symptoms suggestive of irritable bowel syndrome or functional diarrhea.
  2. Recognize the utility of fecal calprotectin as a screening test for inflammatory bowel disease in the patient presenting with diarrhea.
  3. Perform an appropriate initial work-up for the patient with a new diagnosis of inflammatory bowel disease.

IBD EPAs

  • EPA 1: Classify IBD phenotype, disease activity, and extraintestinal manifestations
  • EPA 2: Use advanced diagnostic and therapeutic endoscopic and radiographic techniques in the management of IBD
  • EPA 3: Prescribe and manage evidenced-based IBD therapies using clinical pharmacologic principles in clinical practice

Discussion, Part 2

Current ACG guidelines state that the initial laboratory evaluation for the patient with suspected or newly diagnosed Crohn’s disease should include evaluation for inflammation, anemia, dehydration, and malnutrition [4]. Small bowel imaging should also be performed as part of the initial diagnostic work-up for patients with inflammatory bowel disease, to stage the disease and help differentiate ulcerative colitis from Crohn’s disease in patients with colitis, as in this case. CT enterography and MR enterography are both sensitive tests for this purpose, though guidelines state that MR enterography should be preferentially used for young patients (<35 years) or if it is likely the patient will need serial imaging.

Fecal calprotectin also has a role in monitoring disease activity, and has been shown to correlate with endoscopic indices of disease activity (e.g. SES-CD) [5]. CRP and ESR are less specific than calprotectin, but serial measurements may also be helpful in monitoring disease activity especially if elevated at baseline, and normalization of the CRP during infliximab therapy has been associated with likelihood of continued response during maintenance therapy [6].

In this case, it is difficult to say whether ulcerative colitis or Crohn’s disease is the definitive diagnosis, and the patient may be given a diagnosis of inflammatory bowel disease unclassified (IBD-U, previously known as indeterminate colitis). Though Crohn’s disease classically presents with “skip lesions,” or discontinuous areas of inflammation, pancolitis may be seen. Rectal sparing is often seen in Crohn’s disease, but may also be seen in patients with ulcerative colitis, and has been particularly noted in those with ulcerative colitis and primary sclerosing cholangitis. There is no evidence of small bowel involvement or perianal disease in this case to make a definitive diagnosis of Crohn’s disease, and the colonoscopy findings have features suggestive of both diagnoses. Infectious colitis can also present with similar endoscopic findings to inflammatory bowel disease, however, the chronic nature of her symptoms makes an infectious etiology less likely, especially given she is not immunocompromised and lacks a travel history that might increase her risk for certain endemic protozoan or parasitic infections.

References

  1. Smalley et al. AGA Clinical Practice Guidelines on the Laboratory Evaluation of Functional Diarrhea and Diarrhea-Predominant Irritable Bowel Syndrome in Adults (IBS-D). Gastro 2019;157(3):851-854.
  2. Carrasco-Labra A et al. AGA Technical Review on the Evaluation of Functional Diarrhea and Diarrhea-Predominant Irritable Bowel Syndrome in Adults (IBS-D). Gastro 2019;157(3):859-880.
  3. Mitsuyama K et al. Antibody markers in the diagnosis of inflammatory bowel disease. World J Gastroenterol 2016;22:1304-1310.
  4. Lichtenstein GR et al. ACG Clinical Guideline: Management of Crohn’s Disease in Adults. Am J Gastroentrol 2018;113(4):481-517.
  5. Schoepfer A et al. Fecal calprotectin correlates more closely with the Simple Endoscopic Score for Crohn’s disease (SES-CD) than CRP, blood leukocytes, and the CDAI. Am J Gastroenterol 2010;105:162-169.
  6. Reinisch W et al. C-reactive protein, an indicator for maintained response or remission to infliximab in patients with Crohn’s disease: a post-hoc analysis from ACCENT I . Aliment Pharmacol Ther 2012;35:568-576.

 

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