High-definition white light endoscopy (HD-WLE) does not usually allow the visualization of duodenal villous patterns and may be inaccurate for assessing coeliac disease (CD). To the best of the knowledge of the authorship, there is no prospective study that has evaluated the accuracy of combining high-definition optical magnification (HD-OM) with i-Scan optical enhancement (OE) virtual chromoendoscopy for evaluation of duodenal villous patterns in the context of CD suspicion. Combining both techniques can also guide better duodenal biopsies. This study pursues to compare diagnostic accuracy between HD-WLE and HD-OM with OE using histology as the gold standard in detecting villous abnormalities in CD.

High-definition white light endoscopy (HD-WLE) does not usually allow the visualization of duodenal villous patterns and may be inaccurate for assessing coeliac disease (CD). In addition, HD-WLE findings depend on CD severity. The lesser the disease severity, the higher possibility of showing a normal HD-WLE appearance. Thus, sampling routine duodenal biopsies have been suggested. However, this is time-consuming, expensive, and maybe excessive in low-risk groups. Sampling routine duodenal biopsies could also be unsuccessful, obtaining normal biopsies.

Novel endoscopic techniques have played an exciting role in increasing the accuracy of macroscopic evaluation of duodenal villous patterns. There have been described retrospective and prospective studies using chromoendoscopy, narrow-band imaging, optical coherence tomography, water immersion, confocal laser endomicroscopy, high-resolution magnification endoscopy, capsule endoscopy, and I-scan technology. However, results are disjunct, with no consensus.

The iSCAN optical enhancementTM (OE) System (PENTAX Medical, Tokyo, Japan) virtual chromoendoscopy has been developed to improve the blood vessels' visibility, ducts of the glands, and surface structures in addition to the traditional iSCAN functions. High-definition optical magnification (HD-OM) endoscopes have been developed and can combine HD imaging with OM to produce detailed images with a magnification of up to 136X. This imaging technique facilitates the evaluation of the superficial vascular aspects of the mucosa, enabling the identification of early signs of inflammation or lesions not previously seen with conventional endoscopy.

Prospective data have demonstrated that magnification endoscopy has superior diagnostic sensitivity in detecting villous atrophy compared to HD-WLE, being efficiently handled by all endoscopists. On another side, virtual chromoendoscopy has shown disjunct results across the literature. To the best of the knowledge of the authorship, there is no prospective study that has assessed the accuracy of combining HD-OM with i-Scan OE for evaluation of duodenal villous patterns in the context of CD suspicion. Combining both techniques can also guide better duodenal biopsies.

This study pursues to better characterize duodenal mucosa through OE with HD-OM in gluten-free diet (GFD) naïve patients with CD suspicion to correlate these findings with histology. As a second aim, to compare diagnostic accuracy between HD-WLE and HD-OM with OE using histology as the gold standard in detecting villous abnormalities in CD.

Inclusion Criteria:

• Patients naïve to GFD;
• With clinical history suggestive of malabsorption (weight loss, chronic diarrhea, iron-deficiency, anemia, etc.);
• And serologic suspicion of CD as positive or borderline antiendomysial (normal values are absent for both IgA and IgG) and antitransglutaminase antibodies (normal values 0-10 U/mL).

Exclusion Criteria:

• Presence of severe gastrointestinal or systemic disease (e.g., chronic pancreatitis, liver cirrhosis, and blood coagulation disorders) impacts cardiovascular risk assessment.
• Presence of duodenal ulcer in the context of patients with upper gastrointestinal bleeding.
• History of any type of duodenal surgery.
• Pregnancy or nursing female.
• Refusal to participate in this observational trial.

Adult patients, naïve to GFD, with clinical suspicion of CD who underwent endoscopic assessment.