Table 1.

The Chiu's core classification of small intestine injury.

Classification	Pathological change
Level 0	Mucosa without changes.
Level 1	Well-constituted villosities, no cellular lysis or inflammatory process, although there is formation of Grunhagen's sub-epithelial space.
Level 2	Presence of cellular lysis, formation of Grunhagen's sub-epithelial space and increased spacing among the villosities.
Level 3	Destruction of the free villosities section, presence of dilated capillaries and inflamed cells.
Level 4	Structural destruction of the villosities, only traces of some villosities, formed by inflamed cells and necrotic material, with hemorrhage and basal glandular ulceration.
Level 5	Destruction of all the mucosa, no glandular structure can be seen, only the amorphous material laying on the sub-mucosa tissue.