In clinical practice, we encounter many patients who ask, “What about the severe pain after defecation, what is going on, and what should I do?” First of all, you should go to a regular hospital to confirm the diagnosis, because painful defecation and blood in the stool may be caused by a variety of reasons: 1, suffering from anal fissure. In constipated patients, hardened fecal masses can cut or tear the anus, causing anal fissures. The clinical symptoms of anal fissures are pain and bleeding. The pain is very characteristic, i.e., sudden knife cut-like pain during defecation, then brief relief, followed by prolonged anal pain. Patients are often afraid to defecate for fear of pain, and the vicious cycle of “fear of pain – tolerate stool – dry stool – more pain” occurs. The vicious cycle of “pain – tolerate stool – dry stool – more pain” occurs. The bleeding caused by anal fissures may vary depending on the extent of the torn blood vessels, and it is common to see cases of anemia due to prolonged or heavy bleeding from anal fissures. If anal fissures are not treated in time, three kinds of diseases may appear: anal canal ulcer (fissure fibrosis, also called old anal fissures), anal papilla hypertrophy (polyp-like tumor), and sentinel hemorrhoids (dermal hyperplasia), etc. If they continue to develop, anal sinusitis (chronic inflammation of the anus) and anal fistula (purulent inflammation of the anus) may also appear. The first three are called the “five features of anal fissure”. There is also the possibility of becoming anal canal cancer due to long-term chronic inflammatory stimulation. 2. Suffering from hemorrhoids. Such as stage IV internal hemorrhoids, annular mixed hemorrhoids, thrombosed external hemorrhoids, etc. will appear blood in the stool and painful stool. This is generally there will be anal swelling, sometimes there is a downward swelling pain, but the pain is not as intense as anal fissure, this kind of hemorrhoids form embedded or thrombosis is very serious, can cause part of the tissue necrosis or infection, rupture may cause hemorrhage, must be treated in time. 3, inflammation of the intestine. Polyps of the intestine, tumors of the intestine also have a long bowel time and uncomfortable feeling of blood in the stool. In particular, malignant tumors such as rectal cancer need to be diagnosed early and do not cause irreversible consequences due to negligence.