(1) Anal fissure: The pain is characterized by burning pain in the anal region at the beginning of defecation, which is more intense after defecation than before and lasts for several minutes to several hours. (2) Strangulated internal hemorrhoid: a swelling prolapses from the anus during defecation and cannot be retracted, while severe and persistent pain occurs, and there is a history of internal hemorrhoid prolapse. Wang Qingming, Department of Anorectal Medicine, Shanghai Shuguang Hospital West Hospital (3) Sinusitis: the pain is mild, often minutes after defecation, and can disappear on its own. (1) Perianal infection: persistent pain and increasing distension in the anus or anal canal, often accompanied by inflammatory manifestations, such as fever and increased white blood cell count. (2) Thrombosed external hemorrhoid: The patient suddenly feels a spherical mass, purple or black, appearing at the edge of the anus, caused by rupture of the perianal vein, accompanied by persistent and severe pain, which worsens when walking or standing. (3) Anal canal cancer: there is often mild persistent stabbing pain in the anal area, and in the late stage, the general condition is poor, and a hard lump can be felt in the anal canal. (4) Foreign body in the anal canal: such as chicken bone fragment, bamboo spur, fish bone spur, etc. enter the anal sinus and cannot be discharged, and the pain in the anal region is suddenly severe, persistent and worsens when defecating, and patients usually do not have blood in the stool or inflammation. The diagnosis can often be made by rectal palpation (sometimes rectal palpation under local anesthesia is required). Irritating foods Excessive consumption of chili peppers, garlic, mustard, strong alcohol, etc., which contain irritating components in the stool, can also cause anal pain and discomfort. Other According to the World Health Organization, in recent years there has been a trend of increasing prevalence of sexually transmitted diseases occurring in the anus, rectum, and colon Such as cytomegalovirus (CMV) ulcerative proctitis, a common disease in homosexual men. The main manifestations are anorectal pain, burning sensation, anal itching, mucus and blood in the stool, and urgency. Endoscopic examination reveals rectal mucosal ulcers ranging from superficial punctate lesions to relatively deep fused ulcers with the entire ulcer covered by a light yellow and white wound membrane. Multiple bites for tissue biopsy and viral culture can confirm the diagnosis. Surgeons must also be familiar with the presentation and early diagnostic techniques of these diseases in the anus and rectum. Chronic analgia (1) Perineal descent syndrome: Perineal descent syndrome is a pelvic floor disorder caused by degeneration and dysfunction of the pelvic floor muscles from various causes, which occurs when the perineum descends beyond the normal range during forceful defecation.Parks (1996) first described this disorder and considered it to be a concomitant symptom of rectal prolapse. The main cause is directly related to excessive straining to defecate. Common symptoms are characterized by a feeling of unclean bowel movements, anal swelling, difficulty in defecation and perineal pain. (2) pelvic floor dyslaxation syndrome: pelvic floor dyslaxation syndrome used to be named puborectalis syndrome, and the late pathological changes were mainly spastic hypertrophy of puborectalis muscle. 1985 Kuijpers was named pelvic floor dyslaxation syndrome, which was thought to be caused by normal muscle dysfunction. The main clinical symptom is slow progressive defecation difficulty, defecation can take up to several hours, very painful. (3) Endorectal prolapse: Severe endorectal prolapse often causes chronic anal pain. Endorectal prolapse caused by endorectal fornix can stretch the rectal vault and produce a sense of urgency, thus leaving the internal sphincter in a state of prolonged tension and spasm. Anal pain in these patients may be secondary to ischemia-reperfusion injury to the anal canal caused by pathological hyperplasia and hypertrophy of the internal sphincter.