Patients who have had anal fissure may have this question, why the wound can heal after hemorrhoid surgery, but anal fissure wound is difficult to self-healing? To answer this question, we must start from the pathogenesis of anal fissure. The reason why called anal fissure, because the anal canal fissure and fissure has a fixed location, that is, it is always located in the anal canal of the posterior midline (incidence rate of about 75%), only 15% in the anterior mid, and 10% for the front and rear position. Currently, the latest conception of anal fissures is that they are “ischemic ulcers” in nature, unlike postoperative hemorrhoids, which are able to heal because there is no ischemia (with the exception of postoperative hemorrhoids with anal stenosis). First: the lack of blood vessels in the middle of the back of the anus is the basis of the pathogenesis of anal fissure. Anatomists have confirmed that the blood vessel supply in the middle of the anal fissure is significantly lower than that on both sides of the anal canal, so there is a relative lack of blood flow in the middle of the back of the anus, and the anus, once broken, naturally heals more slowly. Secondly, the external anal sphincter starts from the coccyx and moves forward to the back of the anus, which is divided into two muscle bundles of left and right in a “Y” shape, and then moves forward along both sides of the anal canal around the anal canal to the front of the anus to converge. Therefore, the anterior and posterior sides of the anal canal form a relatively weak area. Third: the anus and the end of the rectum due to the sphincter pull, there is an angle of about 90 °, the angle makes the fecal descent in the process of the anus behind the force is significantly higher than the front, therefore, the rear of the anus by the impact of the chance of fissure is much higher than the other places. Fourth: mental factors. Some medical scientists have confirmed that excessive mental tension or anxiety, can be through the sympathetic nerve excitation of the inner sphincter chemoreceptors, resulting in increased sensitivity of the muscle fibers, when constipation, diarrhea, spicy stimuli, and other factors are very easy to make the inner sphincter spasm. Fifth: spasm of the internal sphincter is the root cause of anal fissure can not be healed. If the occasional constipation damage to the skin of the anal canal, after timely use of medication, such as Chinese and Western medicine wash, apply ointment, oral laxatives, etc., usually the wound will heal. But if the attack for a period of time has not been timely use of medication, it is easy to appear chronic anal fissure. Clinical findings, almost all chronic anal fissure have different degrees of internal sphincter hypertonia and high anal pressure, which is due to the result of the spasm of the internal sphincter muscle, and the spasm of the direct causative factor is due to the chronic inflammatory stimulation of anal fissure. In addition, the spasm of the internal sphincter is not easy to fatigue, even under anesthesia, although anal pain disappears, but the phenomenon of spasm still exists, it is not easy to lift the spasm, so the phenomenon of anal canal ischemia is more serious (that is to say, fissure stimulation leads to spasm, and spasm is aggravated by fissure after spasm). Sixth: long-term, chronic anal fissure, fissure base fibrosis, scarring is obvious; fissure around the inflammatory stimulation and hyperplasia, resulting in fissure on both sides of the skin protruding out of the anus, the formation of a medical known as the “sentinel hemorrhoid” a kind of proliferation of organisms, due to the emergence of the sentinel hemorrhoid, the original fissure drainage is not good, the wound is more difficult to heal. Seventh: long untreated anal fissure, due to the repeated stimulation of pain, spasm of the internal sphincter for a long time, often the formation of fibrosis in the sphincter of the surface layer, the anus appears to be narrowed, defecation is difficult, then defecation will be due to the Nu struggle more heavy fissure stimulation, fissure the more pain, the spasm will be more pronounced, the formation of the vicious circle, with the stimulation of each defecation, the recurrence of the “vicious circle! With the stimulation of each bowel movement, the “vicious circle” will occur repeatedly, and naturally the anal fissure will not be able to heal itself.