Feeling something in the anus may have four conditions: first, hemorrhoids, a common rectal perianal disease, typical clinical manifestations are blood dripping after the stool and fresh red blood on the surface of the stool, accompanied by anal swelling and foreign body sensation. Second, perianal abscess, an acute purulent infection of the perirectal space, mostly associated with severe anal pain, can be palpated in the anal subcutaneous fluctuating masses. Third, anal fistula, mostly secondary to perianal abscess, including internal and external ports and fistulas, the clinical manifestations are mainly persistent pus and fluid around the anus. Fourthly, malignant tumor of rectum and anal canal, there may be no obvious clinical manifestations in the early stage, but when the disease progresses to the advanced stage, there may be a foreign body sensation in the anus due to the increase of tumor, accompanied by changes in stool characteristics, such as diarrhea and unformed stool. Therefore, if there is a foreign body sensation in the anus, you should go to the regular hospital for colonoscopy in the Department of Anal Surgery or Department of Gastroenterology to make a clear diagnosis and carry out reasonable treatment under the guidance of a specialist.