Effect of colonoscopy on fecal calprotectin testing

Abstract

Background: In IBD patients, colonoscopy is essential for diagnosis, determining severity, tracking therapeutic response, screening for malignancy, and making critical therapeutic decisions. A non-invasive diagnostic test is necessary to enhance the filtering of patients who need a colonoscopy. Faecal calprotectin (FC) provides a non-invasive method for measuring disease activity in patients with inflammatory bowel disease (IBD).

Aim: Investigating the effect of colonoscopy on testing faecal calprotectin results after the procedure.

Patients and Methods: In a quasi-experimental study (a before-and-after design), 34 patients underwent colonoscopy after being tested for fecal calprotectin within one week before the procedure. All patients received the same bowel cleansing preparation. FC was measured at 3 points: (a) specimen 1 (FC1): within one week before bowel cleansing by a laxative, (b) specimen 2 (FC2): within the first 48 hours after colonoscopy, (c) specimen 3 (FC3): one to two weeks after colonoscopy.

Results: The FC level significantly increased (p = 0.000) in FC2 in 100% of the study group. The median of the difference in FC levels between FC1 and FC2 was 78 (10-836). FC level increased in FC2 by more than 100 µg/g in 22/34 (64.7%). The greater difference between FC2 and FC1 levels was significantly associated with the colonoscopy's longer duration (p = 0.006). The FC level decreased significantly (p = 0.000) in FC3 to a level lower than FC2 in 100% of the study group. FC3 decreased to a level lower than or equal to FC1 in 20 out of 34 (58.8%).

Conclusion: Testing for FC can be inaccurate and unreliable if performed too soon after a colonoscopy.