The study aims as principal objective to show the association between reflectance intensity of mucosa at different wave lengths and

• the presence of acute or chronic inflammation in stomach or rectum and normal mucosa;
• the presence of glandular atrophy in stomach or intestinal metaplasia.

The secondary objectives are:

• to identify reflectance profile which characterize an acute or a chronic inflammation, a glandular atrophy or an intestinal metaplasia, respectively;
• to find a correlation between the reflectance to different frequencies and intensity of inflammation according to Sydney Classification in stomach (Dixon M F 1994) and in rectum (Erben U 2014).

This is a comparative, prospective, non randomized, controled, mono-centric study.

Eligible patients: patients planned to undergo an upper gastrointestinal endoscopy or a rectosigmoidoscopy with biopsy in the digestive endoscopy unit of Hôpital Ambroise Paré. For patients accept participating to the study and sign the informed consent, they will be enrolled in the study and the recorded imaging of stomach or rectum will be obtained.

Patient management will not be modified in this study as compared to usual endoscopy procedure. Multispectral endoscopy will only prolong the examination 1 minute in order to obtain the imaging. The study consists of video records of endoscopy with white light and the reflected light projected by the fibre introduced 60 seconds in examined channel. This reflected light will be redirected to a multispectral camera.

The endoscopy examinations will be performed in gastric antrum and cardia when theses sites present abnormal position or contour. The biopsies samples of gastric mucosa will be performed in the antrum or the cardia according to the Guideline of the Société Française d'Endoscopie Digestive.

6 groups of patients will be constituted (included 2 groups of control) as described below and compared posteriorly:

• The control group of rectum: 20 patients with negative result of endoscopy examination (-) and negative result of anatomopathological analysis (-);
• The group of 20 patients with positive result of endoscopy examination (+) and positive result of anatomopathological analysis (+) in rectum;
• The group of 20 patients with negative result of endoscopy examination (-) and positive result of anatomopathological analysis (+) in rectum;
• The control group of stomach: 60 patients with negative result of endoscopy examination (-) and negative result in anatomopathological analysis (-);
• The group of 45 patients with positive result of endoscopy examination (+) and positive result of anatomopathological analysis (+) in stomach;
• The group of 30 patients with negative result of endoscopy examination (-) and positive result of anatomopathological analysis (+) in stomach.

Inclusion Criteria:

• Patients needing a digestive endoscopy under general anesthesia, or a rectoscopy without anesthesia, with indicators of systematic biopsy regardless of reason;
• Aged ≥ 18 years;
• Covered by a public health insurance regime;
• Signed consent.

Exclusion Criteria:

• History of gastric or rectal surgery regardless of nature;
• Gastrointestinal bleeding by hematemesis or rectal bleeding;
• Hemostasis disorders preventing biopsy.
• Difficulties in understanding french language;
• Pregnant or breast feeding woman;
• Woman of childbearing age without reliable contraception;
• Adult under legal protection with tutor or curator.