Many patients ask, “What is the cause of the foreign body sensation in the anus?” Let’s understand what anorectal diseases can cause anal foreign body sensation. 1, rectal polyps: occurring in the lower end of the rectum, can be single or multiple, most polyps are round or ovoid swelling with the tip, can be detached from the anus during stool, retracted after defecation. Adenomatous polyps are pre-cancerous lesions, which will develop into rectal cancer if treatment is delayed. 2, rectal prolapse: refers to the anal canal, rectal mucosa or rectum, part of the sigmoid colon downward displacement, out of the anus of a disease, commonly known as prolapse of the anus. 3, internal hemorrhoid prolapse: internal hemorrhoids as a kind of hemorrhoids, early to painless blood in the stool, but the development of a certain stage, there will be hemorrhoidal prolapse of the symptoms. In the first stage, the swelling can be self-retracted, and in the later stage, when it is serious, the swelling can not be retracted, and it is easy to form embedded hemorrhoids. After the internal hemorrhoids prolapse, usually accompanied by anal itching symptoms. 4, connective tissue external hemorrhoids: connective tissue external hemorrhoids because of its form and named, also known as redundant external hemorrhoids. This kind of external hemorrhoid is thickened and enlarged skin folds of the anal rim, there is connective tissue proliferation, the bottom is wide and pointed long, yellowish brown or brownish black, protruding and easy to see, the size and shape are not equal. Sometimes there is only one, in the back or front of the anus in the center, sometimes several around the anus week. 5, anal papillary hypertrophy: often manifested as white papillary swelling at the anal canal, tougher, often more frequent. Anal papillae hypertrophy is mainly manifested as a foreign body sensation in the anus, with the proliferation of anal papillae hypertrophy, defecation can be out of the anus. 6, anal canal inflammation: anal canal inflammation is caused by long-term fecal stimulation and poor defecation habits, such as repeated constipation or repeated diarrhea will cause inflammation of the anal canal area. Because of the existence of inflammation, it is easy to appear anal foreign body sensation.