Swelling of the anus after the stool may be physiological factors, may also be hemorrhoids, sinusitis, perianal abscess or anal fistula caused by, it is recommended to consult the anorectal department in a timely manner, to clarify the cause of the disease and then take the appropriate treatment, can not be based on the symptoms of the private medication. 1. Physiological factors: long-term or recent eat more spicy and stimulating food, or do not develop the habit of regular bowel movements, defecation will be more difficult, dry feces, stool will easily lead to swelling of the anus. 2. Hemorrhoids: when the internal or external hemorrhoids localized thrombus, or combined with inflammation caused by edema, stool extrusion will lead to anal swelling. 3. Sinusitis: acute or chronic sinusitis, in defecation, may be due to squeeze the sinus stimulation, resulting in anal swelling after defecation, usually accompanied by pain, defecation, anal itching and other symptoms. 4. Perianal abscess: Perianal abscess manifests itself as a small lump in the perianal area, severe pain, accompanied by localized fever and swelling. Deep abscesses can also cause generalized symptoms such as a feeling of swelling in the rectal area. 5. anal fistula: anal fistula will lead to perianal pus secretion, can be accompanied by itching symptoms, when the fistula in the formation of abscess, defecation squeeze pus cavity as well as infected fistula, will also lead to anal swelling. After the anal swelling period, we need to pay attention to avoid sitting, eat a light diet and local cleaning, if accompanied by pain, bleeding and other discomforts need to consult a doctor in a timely manner, can not rely solely on the symptoms of the disease, but also can not be used without authorization to deal with the wound infection, delay the aggravation of the condition.