Perianal edema and distension after internal hemorrhoid ligation may be due to perianal tissue trauma, local moisture, poor blood return, wound infection and other reasons. 1. perianal tissue trauma: after internal hemorrhoid ligation will cause some trauma to the perianal tissue, skin, congestion will appear in the case of perianal edema swelling and pain. 2. local moisture: the anus is more hidden and more folds around, the local skin is more humid, the wound for a long time in a humid environment may be white, edema, there will also be internal hemorrhoid ligation perianal edema and swelling performance. 3. poor blood return: perianal varicose veins can lead to hemorrhoids, surgery to remove the varicose veins will lead to local venous reflux is not smooth, the blood accumulates in the perianal area, there will be perianal edema swelling and pain performance. 4. traumatic infection: internal hemorrhoid ligation surgery after not doing a good job of anal cleansing care, after defecation did not wash the anus in a timely manner, may cause traumatic infection, red, swollen, painful symptoms, there will also be perianal edema and swelling performance. After internal hemorrhoid ligation, such as perianal edema and swelling pain is more serious, it is recommended to consult a doctor in a timely manner, to clarify the cause of the disease, and give reasonable treatment as soon as possible.