Table 2. Classification of duodenal histologic changes.

Classification	Findings
Grade I	Normal, no shortening of villi or lengthening of crypts
Grade II	Slight partial villus atrophy; slight shortening of villi
Grade III	Marked partial villus atrophy; marked shortening of villi
Grade IV	Subtotal villus atrophy; no definite villus structure

Adapted from Scott and Losowsky.28