1.Blood routine: decreased albumin level, increased leukocytes, blood urea nitrogen, creatinine, serum transferrin level, fecal flora dysbiosis and fecal leukocytes can be found. 2.Imaging: abdominal X-ray shows paralytic intestinal obstruction and “thumbprint” syndrome, CT shows thickened colon wall in patients with C. difficile diarrhea. 3.Histology Pathological examination: characteristic changes of the colon can be seen. That is, scattered yellow or white oval plaques with clear borders, firmly adhered to the mucosa, flushing is not easy to fall off. The central plaque appears dotted gray-white or tan pseudomembrane, often surrounded by a red halo. The mucous membrane between the lesions is often no obvious inflammation, but in heavy cases can be fused into a patch or even into a tube type. 4, pathogenic examination: such as stool routine, stool culture, visual observation of the shape, volume, consistency and the presence of food residues, mucus, pus and blood of the stool. Different bacterial infection stool can be dilute watery stool, flesh-washing stool, pus and blood stool, blood stool, mucus stool and other traits, confirming the diagnosis depends on the isolation and culture of fecal pathogens.