Diagnostic criteria for inflammatory bowel disease include clinical manifestations, colonoscopy, barium enema, and histologic examination. 1. Clinical manifestations: persistent or repeated episodes of diarrhea, pus and blood stools with mucus discharge, abdominal pain, acute and severe symptoms, and the duration of the disease lasts for more than 4 weeks. 2. Colonoscopy: small bowel and colon lesions can be found, mucosal vascular texture blurring, congestion, edema, purulent secretion attachment, mucosal roughness, accompanied by granular, diffuse ulceration; patients with remission stage colon is pouching sacs become shallow, disappear, and so on. 3. Barium enema: granular changes in the intestinal mucosa; burr-like edges of the intestinal tube; small filling defects in the intestinal wall; shortening of the intestinal tube and disappearance of the pouch sac. 4. Histologic examination: there may be diffuse inflammatory cells, eosinophilic infiltration, acute inflammatory cell infiltration in crypts, superficial erosion of mucosal membrane, ulceration with granulomatous tissue hyperplasia.