In general, the hyperdense shadow in the colon is considered to be intestinal contents or lesions such as fecal mass, intestinal tumors, or foreign objects such as contrast media, extra-intestinal instruments such as metal titanium clips, or implants. 1. Intestinal contents or lesions: (1) Fecal mass: constipation and so on can cause dry stools, less water, causing increased density of fecal mass, which can be seen in abdominal plain film or CT with high density shadow in the colon. (2) Intestinal tumor: long-term diarrhea, emaciation, anemia, blood in stool and other patients, can be considered as intestinal tumor. (3) Gastrointestinal bleeding: gastrointestinal bleeding is often accompanied by blood in stool, vomiting blood and other symptoms, and when a blood clot is formed, it can be a high-density shadow. (4) Intestinal inflammation: local inflammation of intestinal mucosa produces mucosal damage, erosion, etc., and the scar tissue formed after healing, i.e., calcified foci can also be shown as high-density shadow. 2. Intestinal foreign objects: foreign objects that may enter the digestive tract from the mouth or anus, such as metal buttons, etc.; it may also be the contrast agent taken orally during colonography; it may also be the metal titanium clips used for hemostasis of trauma that are kept in the body after minimally invasive colon surgery, etc., which can be shown as high-density shadows. Once there is a high-density shadow in the colon, it is recommended to consult a doctor for a clear diagnosis and targeted treatment.