Skip the scope? A quick stool test could spare chronic diarrhea patients from unnecessary colonoscopies

A rapid fecal calprotectin (FC) assay — delivering results in just 15 minutes — showed strong diagnostic accuracy in distinguishing normal colon findings from significant abnormalities in patients with chronic diarrhea, according to a new prospective study published in the Journal of Gastroenterology and Hepatology. Conducted across 15 clinical centers in China, the study enrolled 556 patients with chronic diarrhea and 152 healthy controls, evaluating FC levels against colonoscopy results.

The test performed especially well at ruling out inflammatory bowel disease (IBD), with a negative predictive value (NPV) of 97.3% at a cutoff of 157.0 μg/g — meaning a negative result can give both clinicians and patients strong confidence that IBD is unlikely, potentially avoiding the need for colonoscopy altogether. However, the test showed limited accuracy for detecting high-risk adenomas.

By the Numbers:

• FC cutoff of 93.8 μg/g distinguished colonoscopic abnormalities from normal/minor findings (AUC: 0.830; sensitivity: 81.9%; NPV: 89.8%)
• FC cutoff of 157.0 μg/g for IBD detection: AUC 0.929; sensitivity 88.5%; NPV 97.3%
• Crohn's disease patients had the highest median FC levels (397.9 μg/g) vs. normal mucosa (59.5 μg/g)

Why it matters: Colonoscopies are invasive, costly, and resource-intensive. A reliable, rapid, noninvasive rule-out tool like the FC assay could meaningfully reduce unnecessary procedures, ease patient burden, and help triage who truly needs further workup.