After rectal cancer surgery, some patients will have anal pain, pain similar to inflammatory stimulation, and cause perianal abscess, pain, or possibly bad anal stimulation, discharge of mucus, similar to nasal discharge, phlegm-like substances, mainly for the following reasons: 1. The location of rectal cancer is relatively low, rectal edema, inflammation, thickening may lead to poor healing of the anastomosis, intestinal fluid, stool, bacteria through the anastomosis The leakage of intestinal fluid, stool and bacteria through the anastomosis to the peri-intestinal area can cause peripheral inflammation, infection and even abscess, commonly known as intestinal fistula and anastomotic fistula. Patients with severe anastomotic fistula need surgical intervention again, while those who are not serious will have perianal pain and perianal infection, which require anti-inflammatory treatment and are resolved by local physical therapy; 2. In the past, sutures were used to close the anastomosis, and if the sutures were not in place, the chance of anastomotic fistula was high, and now the anastomosis is played, and the anastomosis is similar to a staple that staples the two sides of the intestine together. Most patients feel pain because of the low location of low rectal cancer and nerve irritation caused by the anastomotic staple, and even patients with hemorrhoids also experience pain. Such patients can wait until the anastomosis is fully grown, then all anastomotic staples can be removed through surgery or colonoscopy, and the pain will be relieved. Therefore, there are two main causes of pain in the low rectal anastomosis: infected fistula and foreign body irritation caused by the residual anastomotic nail.