Criteria for the scoring histological components: (1) ‘neutrophil infiltration’ (in either lamina propria or epithelium): any number (even only one) of neutrophil(s) is acceptable. (Evaluation under high power view at 40× is required if ‘absence of neutrophil’ is determined. Neutrophil in the lamina propria must be outside of capillary lumina.); (2) ‘crypt abscess’: cryptitis with any number of neutrophils or any amount of neutrophilic exudate overflowing into cryptal lumen AND any degree of cryptal epithelial cell injury.

*If a biopsy has no intact surface epithelium but shows features of erosion/ulceration (eg, granulation tissue and/or inflammatory exudates), also score 1.

†When there are multiple biopsies from different segments of bowel, the maximum/highest/worst score (PHRI_max) among all biopsy sites will be the preferred ‘global score’.