The most important surgical procedure for almost every rectal cancer patient and family is whether the anus can be preserved or not. Anal preservation surgery is a requirement for every rectal cancer patient. Every time, when the surgery is over and comes out to tell the family that the anus is preserved, everyone will be relieved and the patient is relieved to know that his or her anus is still there. However, the painful days that follow are known only to those who have encountered them. There are often post-operative rectal cancer patients who ask about post-operative stool problems, and I talk about them over and over again, but some patients still ask about them one at a time. Complete anal function depends on the soundness of three functions: perception, moderation, and expulsion power. First, normal anal function requires good sensory function. There are chemoreceptors in the mucosa near the dentate line that can sense the chemical stimulation of stool, and there are pressure receptors in the submucosal and intermuscular nerves in the lower rectum and jugular abdomen, both of which sense the chemical and filling pressure stimulation of stool and make a person have the urge to defecate, which is the first step of normal bowel control. If too much rectum is removed, or even completely removed, and the anastomosis goes to the dentate line, so that the lack of receptors often appears stool has been defecated to stimulate the skin to know, even if the rectum has some residual, the anastomosis in the dentate line more than 1cm, because the anastomosis is too low, the warning time is too short, the missile is already in the head, interception is certainly too late. Secondly, a normal anus needs to have a sound abstinence function. That is, when the brain receives a signal of bowel movement and the need to go to the bathroom, and when there are no conditions to go to the bathroom temporarily, it can hold it, which requires a sound sphincter. Generally speaking, most of the sphincter muscles of post-operative rectal cancer patients are not damaged, and the levator and external sphincter muscles should be sound and able to hold, as long as the stool is not too located at the entrance, that is, the warning time is not too short, and the anastomosis is too low, when the stool is felt, the stool has already reached the anal canal, and then the sphincter contraction is useless. Third, normal anal function requires a sound expulsion power. Under normal circumstances when the signal of stool intention is generated, can hold it, and then find the bathroom, sit on the toilet, at this time, all conditions for defecation are allowed, the brain commanded the anal sphincter relaxation, abdominal pressure increases, the anal sphincter relaxation anal opening at the same time the signal to the proximal intestinal canal, coordinated to produce sigmoid colon and rectal pot belly peristaltic impulse (group movement), sequential to the distant propulsion power, prompting The process of defecation is completed by the smooth discharge of feces. However, when the rectum is removed, the healing of the anastomosis allows the pipeline structure of the intestinal canal to be continuous, but the nerves are not linked, just like the permanent paraplegia after spinal cord rupture, the nerves of the healing intestinal canal are not continuous, so that, just like dominoes draw off a card, the transmission is interrupted, the intestinal canal above the anastomosis is usually more scattered movements, less group movements, and the visceral vegetative nerves are not controlled by the brain, so that If a person has a bowel movement and sits on the toilet, even if the anus is opened wide, the intestinal canal above the anastomosis does not have thickened and specialized muscles like the rectal pot belly and has the propulsive power of peristaltic impulse in order by direction, there is no way to smoothly discharge the feces above, and even if the abdominal pressure is increased vigorously, it feels that it is not strong and difficult to discharge. After low rectal cancer surgery, because of the above three effects, almost everyone has this situation: sometimes the stool comes out without knowing it, and most people keep wanting to poop all day long, but they can’t pull out when they sit on the toilet, or a small one comes out, and then they want to poop again after they get up, mainly because they can’t pull out the stool in the intestinal tube above the anastomosis at one time, which is difficult to defecate. For example, a person with ultra-low anus preservation, who takes a bus to go on a business trip, is on the highway and has to poop, what should he do? The next service area is 50 km away, and the driver may not stop for you. In this case, for patients who have undergone a combined abdominal perineal resection, that is, those who have had their anus removed in situ to make an artificial anus, with an anal pouch, there is no worry at all, even more than ordinary people. even more openly. Therefore, there are many patients with low-level anal preservation who go out with their diapers. According to statistics, 30% of the patients with rectal cancer have very poor anal function after low anal preservation surgery, and some of them even ask for fistula surgery again. Therefore, everyone is sure to ask for anal preservation, not knowing that the function of anal preservation has been greatly discounted, and is not the original anus, only after experiencing it.