Half a year after hemorrhoid surgery, the anus has been narrowed, considering that it may be caused by postoperative scar contracture, anal canal cancer, rectal cancer and so on. 1. Postoperative scar contracture: hemorrhoid surgery will lead to scarring at the incision site after surgery due to certain trauma. If scar proliferation or scar contracture occurs, it will lead to tightness at the anal area, which will easily lead to anal stenosis, and may cause certain obstacles when defecating. 2. Anal canal cancer: it is a kind of malignant tumor occurring in anal canal, when the tumor is serious, it will often lead to serious pain around the anus, even there are lumps around the anus, which will lead to local narrowing, and may even block the intestinal lumen and cause intestinal obstruction. 3. Rectal cancer: it is a malignant tumor originated from rectal mucous membrane epithelium, with the gradual increase of tumor, it may lead to the narrowing of rectal area and cause obstruction of bowel movement. Half a year after hemorrhoid surgery, the anus has been narrowed, you should go to the hospital in time to find out the cause and give targeted treatment as soon as possible to avoid aggravation of the condition and cause adverse consequences.