The rectum is located in the pelvic cavity of human body, and its length is about 15 cm, divided into upper rectum and middle and lower rectum. If abdominal pain occurs in the upper rectum, it may show pain in the middle and lower abdomen or left lower abdomen. If the pain occurs in the middle and lower rectum, it may show pain in the middle and lower abdomen or perineum. Most of the time, pain rarely occurs in rectal cancer, but only when the tumor is obviously enlarged, or the tumor has symptoms of incomplete intestinal obstruction or complete intestinal obstruction, most of the pain occurs in the lower middle abdomen or lower left abdomen, most of the pain is vague, but there are also paroxysmal pains, accompanied by abdominal distension and other pains.