Thickening of the mucosa of the middle and upper rectum is not necessarily cancer, but may also be caused by rectal polyps, proctitis and other causes. 1. Cancer: Pathologic examination of lesion tissue biopsy under enteroscopy can make a clear diagnosis. Patients will have symptoms such as blood in the stool, change of stool character, urgency and heaviness, and feeling of incomplete evacuation. 2. Rectal polyps: when the polyps gradually increase in size, the phenomenon of thickening of the mucosa in the upper and middle sections may occur. Common symptoms include blood in the stool, polyp prolapse, accompanied by abdominal pain, diarrhea, pus and blood stool and other symptoms. 3. Proctitis: chronic inflammatory stimulation of intestinal mucosal inflammatory exudation, absorption, tissue damage, repair recurrence, appearing in the upper and middle rectal mucosal thickening. Patients may manifest symptoms such as blood in the stool, abdominal pain, constipation, diarrhea and so on. If the patient appears in the rectum in the upper part of the mucous membrane thickening, should go to the hospital in time to do the relevant examination to clarify the cause of the disease, under the guidance of the doctor targeted treatment.