Before performing the surgery, the doctor may explain to the patient some complications of the surgery and post-surgery, which often make people very afraid and seem to perform rectal cancer surgery as a very dangerous surgery. Rectal cancer surgery is a risky surgery with some surgical complications, but due to the technological advances in rectal cancer treatment in recent years, the risk of rectal cancer treatment has been significantly reduced, but there are still some complications that may even affect the quality of life or even the life of the patient. Surgery-related complications, systemic condition-related complications, tumor-related complications, etc. are commonly encountered when rectal cancer surgery is performed: Surgery-related complications: 1. Surgical side injuries include ureteral, bladder, vaginal and intestinal injuries, especially when the tumor volume is relatively large, the possibility of ureteral injury increases, and sometimes, in order to reduce ureteral injury, ureteral stents need to be placed when performing huge tumor surgery or secondary surgery Sometimes, in order to reduce ureteral injury, ureteral stents need to be placed during huge tumor surgery or secondary surgery to reduce side injury. 2. Postoperative anastomotic leak: anastomotic leak is a very common complication of rectal cancer surgery, especially the incidence of anastomotic leak after low rectal cancer surgery can reach about 15%, and the occurrence of anastomotic leak can lead to complications such as abdominal infection, pelvic abscess, anastomotic stenosis, etc., which may lead to death in serious cases, therefore, for patients with low anastomotic position, it is recommended to have prophylactic stoma. 3. Decreased ability to control stool or even anal incontinence after surgery: As most of rectum is removed during rectal cancer surgery, the ability of rectum to store stool will be significantly decreased, and the number of bowel movements will increase after surgery, and patients will have a sense of urgency to defecate, and some patients will not be able to control gas or liquid stool, and in serious cases, they may not be able to control solid stool, and their quality of life will be low. 4. Sexual function and urinary dysfunction: Since the nerves controlling sexual function and urinary function are distributed around the rectum, these nerves may be damaged when rectal surgery is performed, and about 10-20% of patients develop sexual function and urinary dysfunction, and most patients may be able to recover after surgery, but some patients may not recover for a long time. 5. Stoma-related complications: Stoma-related complications include peristomal inflammation, stoma edema, stoma necrosis, parastomal hernia, stoma prolapse, etc. The specific causes are described later. 6. Abdominal and pelvic bleeding: It may be related to local infection eroding the blood vessels after surgery, which can generally improve with conservative treatment, but serious cases may require reoperation. Tumor-related complications: 1. Tumor cannot be resected radically: When the tumor is large or has invaded important organs, it may not be resected and needs to be operated by stoma alone. 2. Tumor recurrence: Tumor recurrence includes local recurrence, abdominal recurrence and distant recurrence, which requires long-term postoperative observation to detect possible signs of recurrence for treatment. Complications related to systemic diseases: Since there are more elderly patients with tumor, patients may often be combined with diabetes, coronary heart disease, cerebrovascular disease, emphysema, pulmonary insufficiency, liver and kidney insufficiency and other diseases, which increase the risk of surgery. The main cause of death after rectal cancer surgery may be the combination of serious systemic diseases, so a comprehensive evaluation is needed before surgery to reduce the risk of complications in the province for patients undergoing surgery.