Endoscopic indigo carmine spraying for evaluation of intestinal mucosal permeability: Prospective pilot study

Abstract

Background and study aims

"Leaky gut," caused by increased mucosal permeability, plays a pivotal role in various diseases. However, few methods are available to evaluate intestinal mucosal permeability in the living human body. We established a novel method for evaluation of mucosal permeability using indigo carmine (IC).

Patients and methods

Subjects undergoing colonic endoscopy for screening of colon polyps or evaluation of ulcerative colitis (UC) severity were enrolled. IC was endoscopically sprayed in the cecum, and blood samples were obtained before spraying and at 30 and 60 minutes after. Serum IC level was analyzed by liquid chromatographer/mass spectrometer equipped with a Nexera HPLC system.

Results

In both the control (subjects screened for colon polyps) and UC groups, all subjects had their highest serum IC levels at 30 minutes after spraying. Serum IC level was significantly higher in UC patients than in the controls at both 30 and 60 minutes after spraying. In the UC group, serum IC levels at both 30 and 60 minutes were significantly higher in patients with a Mayo endoscopic subscore (MES) 1 at the cecum than in those with MES 0 in the same area.

Conclusions

Endoscopic spraying with IC is useful for evaluation of intestinal mucosal permeability.

Keywords

Endoscopy Lower GI Tract - Inflammatory bowel disease - Diagnosis and imaging (inc chromoendoscopy, NBI, iSCAN, FICE, CLE...)

Publikationsverlauf

Eingereicht: 22. Oktober 2024

Angenommen nach Revision: 19. August 2025

Accepted Manuscript online:
08. September 2025

Artikel online veröffentlicht:
29. September 2025

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